I think, it is a very good decision to fold. Why should you play when you are sure you can't produce the winning hand?
AA is the best pre-flop hand. It is difficult even to think of folding with this hand. But we must respect the statistics of the game. With six hands entering the pot, AA has no chance to survive. Someone definitely will come up with 2 pairs or above.
What the other posts on this thread says? They say: no, never fold with AA no matter what happens next. And fortunately or unfortunately, i am with them. I can't remember I ever folded with this hand.
The thing which bothers me is how a hand like K,5, could enter the pot with all-in? This is not the calculated intelligent poker. We must show some respect to our chips. The game on that table seems to me more luck based.
Since you folded with AA, i consider you as a good player with enough experience.