UFO outside window, waits in backyard

My cousin was staying with us for the Summer.  We were about 13 and 14, then.  She was sleeping next to one of the windows in my bedroom.  I was on the other side of the room, facing away from the window.  We had just turned the light off.  She said there was a UFO outside the window.  I had seen UFO's before.  I thought she was just trying to annoy me.  She said it again, and I got up and went to the window.  There was a UFO.  I told her to get up and run...outside.  We ran out of my room, through the house, and outside into the backyard.  It was still there.  Did it wait for us?  I was disk-shaped with whitish-colered lights and/or glow.  It hovered above us for a few seconds, then took off.  What is so strange, is that we were in a neighborhood where the neighbor's house was only about 15 feet from the window.  The UFO appeared larger than that.  Maybe they can change sizes?
Date may be approximate.  One of two reports from same source.  PD