Question

Riddle me this:

A woman is sitting in her hotel room when there is a knock at the door. She opened the door to see a man whom she had never seen before. He said "Oh, I'm sorry, I have made a mistake, I thought this was my room." He then went down the corridor and in the elevator. The woman went back into her room and phoned security. What made the woman so suspicious of the man?

Answer 1

The man wouldn't have knocked on the door if he thought it was his room.