While I was under the car tonight trying to find anything loose, or any movement in anything in my ever frustrating search for the intermittent rattle, I noticed that there are two square "flaps" off the bottom of the rear bumper, that fold up and clip on. Both mine were unclipped? very odd. I can only assume that they are designed to spring open in the event of a bump?, and that my car must have had a bump at some point?