Fizzboy7

My co-worker recently bought a black 2004 Toyota Tacoma from a used car dealership. It had been detailed out quite nicely, with the paint gleaming and no noticable flaws. As far as I can tell, it had not been repainted. After the first time he ran the truck through a car wash, a foggy haze appeared above the rear fender and along a spot on the tailgate. It didn't have a defined edge.... more like just a couple of spots a foot long that blended into the black paint.
The only time I have ever seen this is when paint is simply fading. But before the wash, there were no fade spots. I am stumped, and he's coming to me thinking I know all this stuff. Anyone have any idea what took place here? Maybe the dealer covered up some previous paint issues and the wash revealed it?
Thanks for any info.