I feel like I'm in a scary movie.

Well, this isn't much of a story, but I would like to hear your opinion. One night I was lying in bed at around 1 in the morning, both my parents were asleep and the house felt lonley and ominous. I turned in my bed and looked at my alarm clock, reflecting to the hallway. All of a sudden, I felt this creepy feeling crawl over my back. I look into my alarm clock, and i see this dense black fog in the shape of a person glide down the hallway. Then, it evaporated into just a thin black fog. This scared me to death and I layed there frozen for a few moments. Then I ran to the door, shut it and locked it, turned on my light, and watched some tv. I sat up and stayed up until day time, so i know I wasn't dreaming or anything. Sometimes I wish I would of been looking directly at the hallway instead of the reflection in my alarm clock, but I still believe it was real and not an illusion.

So, I was wondering, do you think this was a ghost, demon, or what? I know I've never heard of anything like this, so it may sound made up. But believe me, it's defiantly not.