I have to guess that the stud in question was already cracked (or at least, weakened from stress) by over-torquing. Had you or the dealer removed that wheel for any reason, or was it likely last tightened at the factory?
This goes with my conspiracy theory about the factory over-tightening everything
I've only taken my front driver's wheel off so far (to remove the wheel well liner and reach through there while installing the headers), maybe I should go ahead and check them all like the paranoid fool that I am
