I hapened to mine too...
From the factory EVERY bolt is finger tight on the whole dam car.
I would bet that the bracket that mounts between the frame and the rubber/urathane bushing on your rear sway bar is loose. This bracket has 2 screws going into the frame (if thats what ya call it on a unibody car). There is a bracket at both ends of the sway bar.

 

I know the popping you're talking about. I've got an 03, and it mainly does it when I'm backing out of my driveway at a slow speed. I've noticed that it will mainly do it if there is a difference in elevation (like a driveway).

I took it to my dealer and, of course, it wouldn't do it at all! They told me that I still had plenty of time left on the warrenty and to bring it back when it gets worse.

I don't think it's a big deal, but it drives me crazy.