This does indeed suggest that there may be other factors at work. I could try tossing out other ideas, but they would be little more than hypothesis. (Bending

This does indeed suggest that there may be other factors at work. I could try tossing out other ideas, but they would be little more than hypothesis. (Bending during the tipping process damaging the joints in multi-segment launch vehicles? This might explain the difference with SpaceX's Falcons, which I believe do not have joints with O-rings.)