A woman was sitting in her hotel room when there was 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: You don’t knock on your own hotel door and the man did.