Every night I pretty much do the same thing before I go to bed. Tonight however, I was in the bathroom brushing my teeth like I always do and I heard a whistle. Something that you would whistle to get a dog's attention. It was late and there was no one up at this time and the whistle sounded like it was coming from the room I was in, not too loud. Makes me wonder if it was my imagination, a neighbor, or someone in the house. The neighbors were asleep as they have younger children, everyone in the house was asleep, but I know I heard it. Imagination or was someone trying to get my attention?