Underneath it was a little moth...
This picture is from here.
It that had somehow been caught under the edge of the rug. It took me several tries to get the little thing outside since he kept on flying back in before I could close the door. After being outside for not even 30 seconds... he was eaten by a quick-thinking bird.
My morning has not been very good so far. Please, God, don't let this be an indication of how it will continue!