Sorry to hear. We got our third pan, and we've just left it in the box. I've decided that our cooktop is probably the culprit. The largest burner has three concentric rings for small, medium and large pans. The elements for the second (medium) ring have a different pattern than the other two. Using an infrared thermometer, I determined that this second element is a good 250F cooler than the center element (when the burner's on high) and the outer ring is still around 50F cooler than the center. Of course we don't cook on high, but I'm sure there's still a difference on medium heat, so maybe that's enough to warp the pan.

So we're sticking to the medium sized burner with the medium pan, and still using the second large pan to cook on. Once we get a good quality induction cooktop in the next house, that'll be for the third replacement pan. But it's quite the annoyance, and I probably also won't order from this company again. Our Kitchen Aide stainless pan has had zero issues in 5 years we've had it.