Timothy and Rolf-It happened to me and I often use the same set up as you. I contacted Weber and since my Performer was under ten years old, (8), they cover it under warranty.
Thanks for the tip. I have had a WSM for a little over a year now, and I am getting my first kettle grill when I get home from work tomorrow. I don't want to damage it from misuse. I am also trying to figure out how to avoid damage to the plastic rollers on the lid bale. I ahve read they can melt with "normal" use sometimes. Any comments?