Was It a Ghost or Angel?

From: Larry (larryrose20@yahoo.com)
Story type: Ghost
Location: Charleston, WV
Source: Form Submission

I've lived in this house for over 45 years without ever having a ghostly experience. Last year while doing my workout on my ab roller, I had a most unusal experience. As I opened the attic door to set my ab roller on the attic steps, a loud male voice said to me, "Be sure to lock the door!" I looked quickly over my left shoulder than my right, for any signs the tv's might be on. No, there were no tv's on nor anyone else in the house. The questioning I had concerned me, because the door to the attic didn't lock. My brother had lost the door key long ago, when it fell down the wooden door frame. This old house was once owned by a man who lost it during the depression. My older sister had an experience as a child in our attic. She and a friend complained that they had seen a man while up in the attic. My question is this, why did I hear that voice after living in this house for 45 years without any other like experiences? Also, do you think it was a ghost, or maybe an angel warning me?