Where did the strange noise come from?

I live in a big old house. At night I can sometimes hear strange noises. Last Saturday I got home late. I went upstairs, washed and went to bed. My bedroom was very cold and it took me about an hour to get to sleep. Suddenly I awoke. The room was in darkness, and I could hear a sound which seemed to come from the window. I lay quite still and listened. Then I heard it again:" Scratch, scratch ... scratch, scratch. "It came from the waste paper basket. I turned on the light beside my bed and the noise stopped at once. I climbed out and went over to the waste paper basket. A piece of paper near the top moved slightly. Then I saw a tiny gray face and two little eyes stating up into mine. It was a baby mouse. What should I do. He just sat there looking at me, as confused as I was. Carefully I picked up the basket and carried it to the door. The I opened the door and went back to bed. In the morning he had gone.