Have you ever sensed someone else is in the room?

Out of the blue, you are not thinking of anything other then what to have for dinner that day or you could be in the middle of looking at a movie. Your alone, you sense someone is in the room, a chill runs down your spine and you get spooked. Ever happen to you. Happened to me the other night (no I was nt drinking or smoking any wacky baccy) I kept telling myself it was nothing and I was just imagining it. I got up to go the kitchen and let my dog out the back door, the dog looked into the room I had come from and barked!! yep.. My skin went cold. Dog kept looking into the room and then after about 8/10 minutes, I sensed whatever it was had gone. At exactly the same time as I got this sense the dog got up from the door of the room and up to her bed to sleep. Strange. Still trying to convince myself it was nothing, but just like to know if this has happened to anyone else out there and what you thought it was. Thanks. :)