Glad you found him - always look under/in the heated spots first! I lost a baby corn snake twice last year, before realizing her tub had a small crack (just big enough for her to escape)... both times I found her under my adult BP rack, the warmest spot in the room & first place I checked. Gotta think like a snake, LOL.
P.S. How do your roommates not know about the snakes? I can see a landlord not knowing, but hiding them from a roommate would be tough!