Yes, SearMagic grids can warp.
Warping is usually caused by cooking with a burner that has a split in the seam, allowing a larger flame to come through at the split. This is called a hot spot. When a burner starts to split, it needs to be replaced. Otherwise, the cooking grids will continue to warp.

How do I fix warped SearMagic Cooking Grids?
To fix warped SearMagic cooking grids, you will need to heat them in the grill on high for about 10 to 15 minutes.  Using oven mitts, remove your grids one at a time and wrap in an old towel. Next set them on a flat surface such as a sidewalk and press down on the high spots until flat. You may need to repeat this process several times depending on how severe the warping has become.

The way to keep the cooking grids from warping again is to be sure to inspect your burner at the beginning of each grilling season and replace the burner if the seam starts to split.

The warranty covers the cooking grids against a manufacturing defect, such as a weld pop. The warranty specifically excludes warping, which is explained in the Maintenance section of the owners’ manual.