I fell on a brand new 0.5 C4 and had very similar results when they first came out. The fall was a swinging one, about 5'. Nothing serious, but the irregularites in the crack and the rotation of the cam's head caused an axle to bend and one (maybe two? It was years ago) of the lobes was locked in the closed position. It held my fall, and I finished the route by running it out over the same piece. What I learned wasn't that BD had a design flaw. I learned that to stay safe it is absolutely critical that you inspect gear you fell on before heading back up, and that even well designed gear can unfortunately be damaged in real world applications.

Josh