Anyone believe in Ghosts ?

A personal story, lately we have expanded our garage with a bar, big screen and surround, any we have been known to have a couple there among friends. Some how our house dead bolts seams to get locked and lock us out. The other night my wife was in the garage with a few of her friends and came in to talk to me on the couch and then went back to the garage. I got up to get a water about 45 min later and the dead bolt was locked again. You have to lock this from the inside, and this locks hard, so it just wouldn't lock buy it self. It is definitely freaking us out it has happened 3 times in Dec. alone. Might have to hire one of those shows to get to the bottom of it.