If I remember correct, only the left side of the seat holds the seat back from tilting, the right side is just a pivot point. I had a 93 GMC that has a similiar seat mechanism, that was real bad, I took it apart and bent the bracket back to the correct position, just not a very sturdy bracket.
My GN seats have the same problem, only way to fix would be to remove the seat, remove the cover, and fabricate some kind of a bracket reinforcement to keep it from bending.
If your a bigger guy and lean back hard in these seats, it doesnt take much to bend the seat back, not cool.......