Oh...and to answer a couple more questions (had Mites on the brain! LOL)...
Live mice are fine. And feeding in his own enclosure is fine, too. Just be careful and don't ever leave a live rodent unattended with your snake. If the snake doesn't strike and eat within the first 15-20 minutes...then remove the mouse and try again a week later.
The main concern I would have with him having been on the loose for a week is the possibility of developing a respiratory infection due to long-term exposure to cold temps. It's not a certainty that he would develop one...but it's a possibility. Over the next couple of weeks, keep an eye out for the following symptoms:
-- Whistling, wheezing, or popping noises when he breathes
-- Mucous or other liquid building up in the mouth (sometimes they will dribble water right after a drink...don't let that scare you! LOL)
-- Laying with the head propped up at a sharp angle all the time
-- Constantly rubbing its face along the sides of the enclosure or "furniture" within it (while not in shed)
-- Trails of slime on the sides of the enclosure
Such signs would mean he needs a trip to the vet for a round of antibiotics.