I have never put Tupperware or Rubbermaid or Sterlite in the dishwasher. Hand wash it all so I don't have personal experience with warping. My question is this: since no one claims to have taken off with my large white round bottom for my Tupperware storage container at a family picnic a few years ago, would Tupperware replace that to go with the top I still do have. Haha.
Good luck, I do remember being told at parties years ago that lids could be replaced free of charge if warping or damage occurred.