I had a simular experience a few years ago. It was late at night. I was watching a DVD of "Muteny on the Bounty," and the door bell rang. It was bout 11 ish at night, so I wondered who it could be. It sort of "wierded me out," too, so I grabbed my pistol before I answered the door. When I opened the door, there was nobody there.
As it turns out, there were a group of teenagers out playing themselvs a game of "ding dong ditch" that night, because my neighbors told simular stories. But for some reason, I was just a little spooked.