Do you think you're twisting/torqueing the frame, cranks or BB when you climb? Is there any noise or weird feeling? I'd find this quite unlikely, and would be checking the FD's limit screws as previously mentioned.

But check the tightness of everything else down there, and alignment of the rear wheel. Take it all apart, grease (or anti-seize) where you need to, and put it back together again, etc.