I decided to have the other LBS take a look at the hub before I put it back together. They said it was toast as the threads that the freehub bolt mesh with were damaged.

They didn't think it seemed likely that the problem was a result of me overtightening the bolt and recommended that I go back to the LBS I got the bike from and see if they'd warranty it. After waiting about an hour they told me Shimano declined to warranty it and that it would cost $110 to rebuild.

I went back to the other LBS and they told me that without question Shimano would warranty the part, but I'd have to pay for labour. So rather than pay good money for labour to rebuild a generic OEM rim I'm going to pay the difference to have them put the new hub on a Mavic A719 rim with quality spokes / nipples.