In the long-term, at 50NL, if you NEVER fold a set on the flop, it will be a ++EV play. You got "lucky" and made a good read or guessed right, but being proud of this play is results based thinking...the 'right' play, in terms of EV, taking the table stakes into consideration, was to call or raise (not sure if you would have been all in). I have said this before and will believe it indefinitley...for 100BB or less, there is no good reason to fold a set. To fold here is the very definition of weak tight - you'd have been better off folding preflop.

I would never fold it , at 50 nl, no way
if he has the better set God bless him, I will curse the site, his mother, whatever, but I will not fold

When I get oversetted I usually get that "feeling" in my stomach and when they turn it up it rarely comes as a surprise. People go hog wild with sets and when pot sized bets start to flow on dry boards, from decent players, it screams set to me. While I have only folded a set to the action described in this hand maybe once in my poker career k3nt brings up a really valid point. The big hands I lose where I know I am beat, but still call anyways are a huge leak for me. I just can't bring myself to lay down that set or my underfull on a non threatening board even if I am 90% sure I am behind. Though folding in this spot is a losing play if done everytime I don't see how you could possibly say it's a bad line, he folded when he was behind. Making a good fold is money earned in my book.

-Moose