Woke up this morning to find a rusty cover on the underside of my WSM's lid and the inside body. The previous owner who used it many times never got this residue. The only thing I changed was covering the underside of the water with foil. Could the foil be causing some reaction or maybe to much moisture. Its just weird that before he coating was nice and black like my old Chargriller and now I'm getting this rusty color. I had to use a Scotch-Brite to get it off. Here are some pics. Oh, and by the way the charcoal bowl was fine no residue. Weird.