Goose neck separated!

The goose neck on my boom came apart yesterday. The good news is that it happened just as I was heading up wind, shaking out a reef! What would have happened under load? I assume, given the size of the bolts, there is not a lot of pressure at the foot? Anyway, the bolt doesn't appear to be broken to me (though, the end is not completely smooth). Looks like the nut simply came off. Thoughts? I'm going to pull it apart and see whats in the boom, but just wanted to get input first. Pictures are of the mast end of the boom and the goose neck.