I have a 4x8' (49x97") sheet of 1" MDF sitting in my garage that has been cut into two 4x4' sheets. I was just looking at them and they don't appear to be completely flat any longer. They have been sitting on edge in the garage for the past few months waiting for me to start building my Adire 281s and 81s. I just was wondering if it's possible for MDF to warp? If so, can MDF be flattened again? Thanks.