I dunno if it's relevant or if it's just coincidence, but my last rescue was riddled with mites and he was fed live mice. I've never had a problem with mites and I feed F/T only. Possible the mites are hitching a ride on the mice?
While snake mites don't feed on mammals, if the shop where you purchase your mice has a mite infestation then it's possible to bring home a hitchhiker.