gecko5, I have a little bit on the underside of the tailgate, just a little to the left of center. It is coming up from under the paint, as the paint is unbroken. Started as a few spots that looked rust colored on white paint. I looked yesterday,turned around facing rearward, and can see that it is at the lip where the outer skin is folded over the tailgate inner sheetmetal. Right now, it is about 4-6 inches where the paint may have barely separated from the metal and one spot about 3/4" upward from the joint where the paint is discolored about the size of a quarter, with spots inside that diameter.
I plan on scraping the paint away where it has been loosened by the rust, applying a rust 'converter' and painting. Maybe remove the inner panel to see if the insides of the tailgate are rusting.
I know I have no warranty, as it's 4 years old, but this is poor quality.
tom