after a couple playthroughs of the campaign my tiles are starting to get a little warped. I have not done anything to intentionally bend them and have stored them nicely. are there any ways to un-warp them or prevent warping?

Weights? I have not seen this with my, but most likely humid warm temperature is the enemy of cardboard elements. But you may try to put them under pressure. Heavy books etc.

I find mine warp a lot when I'm playing in front of my air-conditioner on heat. They normally go back to normal by next game. Try stacking them all with something heavy on top.