I would suspect that the bolt was not torqued enough rather than too much. Both the bolt and the crankshaft end will be hardened steel. If the bolt was over tightened you'd have to go a long way to stripping the threads. It could have been cross threaded, which would have given a false torque reading, but the interference threading should have prevented the bolt from backing out. If you thought the bolt was tight it may have been just cross threaded. If the threads are damaged then you may have a major problem. The bolt is easily replaced but if the threads on the crankshaft are damaged, <img src="/forums/images/graemlins/scared.gif" alt="" /> !!! I would inspect the threads in the crank very carefully. You could even run a tap to make sure they are clean and to somewhat repair any damage. I don't know if the crank bolt recall was an issue with your vehicle, you may want to check with the dealer. You may also want to use this opportunity to do a timing belt change and crankshaft seal. Best of luck.