Originally Posted by JARblue

It's not the liner that gets warped. I've certainly never had any issues in the Texas heat. But the heat does get to the clips and they get brittle and break easily. Typically they'll hold together until you remove them at which point they'll break, but sometimes they'll just break on their own from vibration. I replace clips all the time; I rarely am able to reuse clips I remove but even when I can I go ahead and replace them with new ones. I'm guessing I have probably replaced every clip for the fender liners at least 4-5 times over the life of the car; going on about 15 replacements of those three clips in the middle of the undershroud.