Yeah, I was afraid that's what you were going to find. Once these other guys from up north posted and I thought about salt and the location where you described, I figured it was inevitable.
The condition I first described tends to happen on the hood and roof, the areas most exposed to the sun. I'm sure you've seen vehicles where the clear or both the clear & paint are bubbled up and you can basically peel the clearcoat off. Eventually the paint bubbles burst and you get pure out rust. That's what we get in the deep south...