Write a story that seems normal on first sight , except for one small detail that makes it extremely creepy on a more careful reading [ WP ]

A sound wakes you up in the dead of night. It sounded like a knock on your front door. It's three in the morning, you're sound asleep in bed. The house is dark, the lights are off. You're all alone. You look out the window and see the dark clouds swirling, in preparation for the rainstorm predicted for tomorrow through the clear glass pane. 
 
 You get up to investigate the noise. You check the doorway. Nobody. You open the door and peek around outside. Not a soul in sight. You check around the porch. Still no one. Maybe your grogginess caused you to hear things. 
 
 Annoyed, you shake your head, shut the door, close the window, and head back to bed. 
 

