I'm not sure if anyone experienced this, but when I am in my master bathroom sometimes I suddenly hear water runing through the pipes as if someone is running water in the house. But It may be 12am an no one else is up or at a time when I am the only one home. It last a short time then stops. The pipe also bangs when it stops. I am not sure what might be causing this. Any ideas?( don't tell me I have ghosts)