First of all Chris, I'd like to congratulate you on keeping your mentor in the loop, that was obviously the thing to do. You came in as a collaborator to the wedding photographer and this would make it obviously wrong to turn yourself into a competitor for the same event, wouldn't it?
It seems to me that the take away from this thread is that in such professional situations, it pays to be diligent and to make each parties expectations clear beforhand. That and not to confound being confident and being confrontational or arrogant. Being confident will move you forward. Being arrogant might also move you forward, but you also risk having to drag a burden on the way.