I learned something new and very important today at Williams-Sonoma: Never cool a hot pan in cold water or on a cold surface.
It causes thermal shock. Because rapidly lowering the temperature of a pan like that causes it to warp. Warping makes it so that the pan won’t sit flat and can “pop” when heated back up.
(Gosh, I wish I knew that last year! I’ve gone through three jelly roll pans and the latest one is warped!)