Just wanted to post an update on the situation. I picked up the snake on Tuesday and set him / her (don't know which yet) up in a 10-gallon with the right thing. Left him alone for a while. When I got to checking on him earlier today, he was slithering around the tank like he was hungry. I tried live, but he didn't want it. I tried a pre-killed, never-frozen mouse, but he didn't want that either. Thawed was a no-go as well.
He seems to enjoy whipping me with his tail, although he's showing absolutely no other signs of aggression. Upon closer inspection, there are no mites or parasites, and he left urates in the tank (but no poop). Overall, I think the little guy will be okay. Probably just scared and wants to be left alone.
A visit to the vet in scheduled for tomorrow.
Give him a week to settle in and I am sure he/she will be pounding down the mice! Usually the first few days of slithering around is more of a "OMG WHERE AM I" slithering around as opposed to an "OMG I AM HUNGRY" slithering around.