This is funny timing for this conversation ... I've been watching mine just for this problem and saw it happen on Thursday, but never thought about putting it on the forums. This is my third white vehicle in a row, a '99 GMC Jimmy, a '05 Chevy Silverado and now the '11 V6. This is the ONLY white vehicle that has changed color on the fiberglass/plastic parts and it's managed to do it since October while being parked in the garage from November to April.
The difference between the Chevy and the Ford is quite noticeable since they sit next to each other in the garage, the Chevy being more bluish white than the Ford's creamy white. I had the Mustang in the driveway after a wash and the front fascia has a definitely different cast to it than the painted metal parts that's easy to see up close and from the house about 15 feet away. We had paint/surface protectant put on the entire car inside and out when we bought it so I thought maybe that had something to do with cast change but now I'm not so sure. Great, now it looks like I'm calling my dealer about a jack AND the paint change this week.
2011 V6 Premium MT - Performance White Pony Package
To quote the Tubes: "She's A Beauty"