Yeah, I had mites come in once on (I suspect) a bag of rodent feed or bedding. They can hitch rides on clothing--they don't live long, but they wander far, so anything near a snake with mites may have mites on it.
It's a good idea to keep a can of PAM on hand in case of an issue. I don't treat my bins as a matter of course, as that seems unecessary and expensive--I treat the floor and legs of my racks with flea spray now. It's not safe to use in areas the animals come in contact with, but works fine for places they won't be touching, and creates a formidable barrier to mites that might come in on supplies. The PAM I reserve for treating the bins of new animals in quarantine, and keep in case anything slips past the defenses.