Hi,
I wouldn't leave live mice in with a snake unattended - if they bite and chew on the snake it stops the feeding response and can end up very very bad. We have pictures but trust me you really don't want to see them.
Did his temps stay in the right range?
Does he make any sounds when he breathes and, if you gently open his mouth, is there a lot of bubbly mucus in it?
dr del