Jim,
No, I don't run with the pan empty, which would explain the bowing.
I noticed it Sunday, when I inverted the empty pan onto a flat surface, and one side of the pan lip, sits about 1/2" above the flat surface. I have never checked this before, so it's possible I bought it that way, and never paid attention to it.
One thing that it does inhibit is filling the pan full of water. Dependent upon where the bow is located when the pan sits in the cooker, it's possible that when filling the pan to the tip top, on one side, it overflows on the other side.
Making my fire, an unhappy camper. /infopop/emoticons/icon_smile.gif
I have the larger ECB pan, somewhere, now to remember just where?
Jim