maybe so, but in this case, I doubt it. you can't sprint with an unclipped pedal. you would slide off very quickly.

it was probably a combination of a worn cleat, too low tension (since it was a cheap SPD, this definitely can happen), and twisting during the effort of the sprint. the spd m324 is a crappy single-singled pedal with a cage on the other side: http://www.amazon.com/Shimano-PD-M32.../dp/B001AT33CW

speedplay frog will solve this and let you keep using your existing shoes. if your shoes do have both 2- and 3-bolt capability you could get a speedplay road pedal instead. my wife rides the frog and loves them.