Looks like the lid warped on you. That happened to me when I tried burning the paint of to. So the next lids I did by hand with a grinder and they stayed nice and flat.
Drumhead - UDS x 2 & UDG
Keep on Smokin'
KC native missin' KC
IMBAS Certified MOINK Baller 2009
I also support PETA - People Eating Tasty Animals