For any other cat, this would not BE weird. My cat used to sleep on windowsills as a kitten. He rolled over one day and hit the corner of a table with his lower back. For three days his hindquarter's were unable to move. He still has problems with it today, (Do NOT pick up the cat. He bites if you do, but who could blame him?) but he doesn't sleep in windows anymore. I did find him asleep in the washer, I left open, a while back, so I guess he is not the brightest bulb on the tree.