I take it you and your roomate don't get along. I know that me and my roomates take each others shit all the time and we don't care. I have my peices on a shelf and they take them all the time and return them. The only thing I ever get mad at is them not getting me to go smoke.... The situation probably went like this:

Oh shit I ran out of papers... Well god has a pipe and its probably in his desk. He probably won't mind if I borrow it to go smoke a bowl.

Not very much malice.. so calm down