Reptile mites and the mites you find on rodents(or in the bedding) are different mites. You won't give your snake mites off a rat with mites.

(this is not to say that a snake mite might not hitch a ride on a rodent from store to home, same as if it might hitch a ride on your pants leg)

Rodents can get lice or a type of mite, in addition to fleas. Just remember whatever you use to treat can transfer to babies, to the bedding, etc... and thus to your snakes. So be wary of what you use if the animals are intended for feeders, or if they are being used as breeders and the babies are exposed to the freshly treated parents.