[RobSutton]

I'm not sure the mites would have been biting - they were probably just hitching a lift. The technical term is phoresis. The mites would have been feeding on the debris in the old nest and when the queen flies off to hibernate some of the mites go with her so that when a new nest is established next spring the mites drop off and feed again on the debris. You see a similar thing with dung beetles where mites hitch a lift from dropping to dropping. It's not in the mites interest to harm the bee or beetle, just think of them as harmless hitch-hikers trying to play their role in the ecosystem.