Like I said, Im sure it happens but Ive never seen it. I lived in Texas with blackouts and mine never warped. To many variables I guess.

 

It happens on Camaros all the time, more regularly on 97+ taillights. I've seen a handful here in Michigan that have it, and there's been discussions about it on LS1Tech.com about the blackouts trapping the heat. It's always in the same exact spot, too. It's no urban myth. One guy on LS1tech said he's seen warped taillights on every single B4C since 93 -- and they don't even use covers! Generally speaking, you're going to see warped taillights from prolonged night use, if you use the brakes a lot, and in an area with high temperatures. With certain blackout covers, you're just increasing the heat being kept in the taillights, thus increasing the chance of warping.