Thanks for the info. I did have it replaced by my ford dealer under warranty (the wiper blade fell apart and scratched up the glass) and I hadn't mentioned the issue earlier, so I should be in good shape. I didn't mention the sound to Ford earlier because it was one of those things that didn't happen all the time. I didn't want to get there and look like a winer. Now that the sound is obvious and consistent, I think it will be easy to make the case. I've heard from the dealer that the Edge is a "noisy" car to begin with, so I just wanted to see if anyone else is experiencing this sound (crack/rattle).
Thanks!