Snake mites can be passable by prey if you toss one in right after. I think I could safely assume they could spend a period of waiting on their mouse host to find a new reptile host. I think it is also safe to assume that if you treat all reptile spaces and your mice for mites ( with approved safe treatment methods) that you should have no issues.

As for space, I keep my corns and kings in 32 Q sterilite tubs. I would consider downsizing the dish but other than that it seems fine. I feed live but never leave it in for longer than 10-15 minutes, if they haven't eaten by then they wait for the next feeding time.

The vets we have in our herp society recommend 3 months quarantine.  I think most would recommend empiric mite treatment for your situation, and some would recommend a Provent-a-Mite treatment for ease and convenience.

I think the section on dealing with mites in the book, Understanding Reptile Parasites, by Roger Klingenberg, 2nd ed. is really informative (BTW he recommends a minimum 30 day quarantine).  It certainly helped me when I had a mite problem.  Along with a nicely detailed section on a bunch of mite treatment options (including Provent-a-Mite and how to use it), it also goes into food as a source of infestation and treating rodent colonies.  You can certainly spend time trying to figure out if you have mites, soaking the animal to see if drowned mites are present in the water, repeatedly running your hands along the snake's body to see what remains on your fingers, etc., but with the story you told and likelihood of exposure, empiric treatment seems appropriate.

When I found mites I went crazy and ordered a case of Provent-a-Mite (I decided it was most convenient option for me), sprayed every surface including the floor and rafters, treated every animal in my collection three consecutive weeks, switched entirely to newspaper away from substrate and sprayed each sheet before lining the cages, cleaned every cage with 3% bleach every week for about 5 weeks before spraying all interior surfaces with Provent-a-Mite and Bioshield...  I don't know how much of it was really necessary, but I read a bunch and asked experienced people what to do, and that's what I ended up with.  Seems to have been successful, I think I had the mites in the Spring this year.

Provent-a-Mite is pricey, the book describes much less expensive alternatives.

I'd start with soaking the animal in a clear or light colored tub for awhile - mites drown in water and you should be able to see tiny black specks on the bottom of the tub after.

I would suggest using Provent A Mite just as a precaution. That stuff works wonders, I had a full blown case of mites and PAM was amazing!

Thanks a bunch everyone.  I am familiar with PAM but haven't used it since my last collection.  I know it's smart to use it as a preventative measure too.  I'll make sure I get on that.  I have been giving him a good look over every night since I have had him and I cannot see anything.  I will continue to leave him quarantined but at the rate I'm going, I will end up having quarantine areas all over the house!  :)

The main thing to remember about PAM is that in aerosol form it could be toxic to your animals.  So whether you're using the saturated snake bag technique or the substrate coverage technique, make sure your animal has no chance of inhaling the aerosolize chemical.

I use the fronline mite spray.  I've learned a lot of people on here are against it, but my vet reccomended it to me (and no my vet isn't a dumbass...actually very high up there in the medical world) so I trust him.  It has treated every snake I've used it on, the first time.  We always do a second time around treatment just to make sure we haven't missed any, and we've never had mites problems probably because of how thorough we are when we bring new snakes in.  That's the first thing we do is treat them for mites regardless of whether we find any or not.  If your guy is albino you'll definitely be able to see them a lot easier too.  With ever snake I've ran into with mites, I've found they like to hang out the most up by their neck and head and mostly under their belly scales.  So you can check every few scales or so on his belly to see if you see any black spots.  Like bka momma said.  Do long soaks that submerse the snakes belly that way they drowned.  Just keep an eye on the snakes attitude.  Keep it away from your main collection I would say for 30+ days and of course wash your hands.  See how he eats, how often he poops...the normal quarenteen stuff.  You might have literally lucked out.  Only time will tell, or a visit to the vet.  Good luck.

Oh and just my opinion...I'd take his wooden hide out and throw him on news paper or paper towel substrate.  Mites can burrow into wood so if he does have mites and you treat him...you might end up with a reinfestation because of your hide.  You can go to www.beanfarm.com and get some nice plastic hides that have a bowl built into them.  They're a little spendy but worth it because they're durable and save space.

+1 to Megan and the frontline spray.  I definitely wouldn't use it on an animal that has high humidity requirements, as they seem to react poorly to the use directly on the skin, however I've never had problems on Kings, corns, boas or ball pythons.  I also second her suggestion to get rid of the log hide and the aspen until you're done with mite treatment, which in my opinion should take no less than 6 weeks as the life span of a mite is 45 days.

The great thing about PAM is you can pre-spray cage liner-papers and store them for up to about 6 months out of heat and light, I believe, and they retain their effectivity, though, with normal feeding schedules, you'll go through them quicker than that.  I use frontline on fosters that come in with a visible case of mites, and ALL the fosters in my house live on PAM treated papers.... of course, remember that whether you use PAM or Frontline to treat your cage, it has to off-gas for about 45 min, before you return the animal to it's enclosure.

Whether you should keep him in a tub or a tank, I have found that when I've had kingsnakes in the house, they'll use every inch of tankspace, vertical and horizontal, that you give them, tho, they do not seem adversely affected by tublife either so I think it would be whichever you prefer.

Good luck :-)