I often find it funny in a way when unexplainable or odd things happen. Then resulting from whatever happened people start finding it weird or amazing, and even scary. People then try to figure out what it was or how it happened.
Like Zebrah said it could be an animal that came in through the window, or it could have been a ghost, or could have been gravity, physics, or a myriad of other things.
The thing is.. these things aren'r just going to stop happening from time to time, so why, what's the ponit in trying to figure out or explain the unexplaiable. Of course life needs mystery and excitement, but these little things seem so trivial and small. Now when events happen on a larger scale that's when people should be trying to explain them or at least attempt to, to satisfy their curiosity, to relieve their fear or panic of the unknown etc. But for the simple things why not just accept them as part of life, as which they are.