What started off as (seemingly) a chip in the paint from a small rock, has turned out to be much more. We found some white touch-up paint and used it to cover the exposed gray (not sure if its the primer or the metal). After washing the car a few more times, the area (on the top of the car, in the center left to right, and just a few inches above the windshield) began to get bigger...and bigger...and bigger! It is currently about 6 inches in diameter, and growing.

I've read other articles/comments on other sites that there is a known issue with the paint/primer bonding to the surface beneath, and have seen this demonstrated on many other Impalas on the roads.