Mites are horrible, I had them get into my collection once--thankfully they didn't get very far before I caught them. I have no idea how, because they weren't on my quarantine animals, and I didn't introduce anything new! They must have hitched a ride on a bag of feed or bedding from the pet store.

I treat quarantine bins as a matter of course, now, in case anything comes in with them. That way they can't spread.

It's a good idea to inspect your animals regularly, and just keep an eye out, because they can hitch a ride on your clothes...you never know.