Something very wierd happened to me today?

About 1:30 this afternoon I was in my bathroom and heard water running. I thought it was the toilet, I jiggled the handle inside the tank, but that was okay. Checked the bathtub hot and cold and that was find the same with the bathroom sink and kitchen. All were fine. Went into my basement and the noise was louder than what I heard in the bathroom. I could hear water running inside the water lines within the basement. In the Fall I had turned off the valves that went to the water supply to the two spickets I have on the outside of my home. These valves are in the basement. One on each side of my basement since one spicket is in the front of the home and the other in the back. Well I had to leave for work so I couldn't spend any more time trying to figure out what the heck was going on. I can home 3 1/2 hours later and went out in my back yard and saw that the outside back spicket was running at full force, water was coming out big time. I had removed the hoses and turned the nozzles off when I turned the valves off in the Fall. Can not figure out how this hapened. These water valves and spickets have been turned off for three/four months and not a drop has come out and then today this happened. Can anyone explain to me what might have happened to cause this. When we went to turn the nozzle off where the water was coming out, it was completely turned in the on position but noone touched it. We have a ton of snow in the backyard and there were no footprints so noone could of turned it on. Please help.