ANYWAY... I didn't want to sound ignorant, but I thought it was because they were both Brazilians that Nog took it more personally. Nog said something like "I respect you, why would you disrespect me?" This pretty much sums up why he got upset. Towards the end of their argument, Nog was even backing off a bit and said "It'll be my pleasure to ask for forgiveness if you didn't say anything. Until then leave it alone." How much more classy can you get?!
That is exactly how I saw it too.
Nog showed respect for Vinny; perhaps they talked earlier, perhaps Nog wanted to train with him afterwords. I am not sure.
What I do know is that Nog clearly felt disrespected when he heard that one of his own countrymen was smack-talking behind his back, especially someone who he respected.
Imagine you wanted to play in the NHL. You happen to be the best skater in the world. You can skate faster than your coach, but are ammature in terms of puck handling, passing, shooting, positioning, and general knowledge.
Would you diss your coach behind his back because you happen to excell at skating?
Now I realize Nog wasn't Vinny's coach, but there was potential in the future, and Vinny has possibly slammed a door shut on possible future training with Big Nog.