To prevent this I keep a couple cans of nix spray (exact same active ingredient as PAM) on hand.. It is $5 at Walgreens for their generic brand of lice bedding spray. Use in the same way as PAM. Let everything dry and air out for a while. I wait 30 minutes before putting snakes back in.

After the initial treatment, just spray a line around all tubs, racks, floorboards, door ways, and anywhere else they can enter the area but you won't need to treat the insides of the enclosures again. Do this about once a month. This way you will never get mites, or any bug for that matter, anywhere near your snakes and you don't have to needlessly expose them to continued treatments of chemicals.