Absolutely. His reluctance to have people touch his scar and the fact that in “Zuko Alone” he starts having flashbacks of the trauma surrounding his mother’s departure, are good indicators. But there is an even more telling sign of it when he battles Zhao in “The Southern Air Temple.” Iroh first calls attention to it by saying, “Have you forgotten what happened the last time you dueled a master?” and Zuko responds, “I will never forget.” The camera focuses on the scarred side of his face.
Then comes the Agni Kai itself. Zuko is on the defensive almost immediately, helplessly blocking one fireblast after another after another. He can’t break Zhao’s root; he gets knocked off his feet and it looks like the fight is over.
Zhao dives in for the attack, from above, with a fist full of fire, right at Zuko’s face. Just like Ozai did in the last Agni Kai he participated in. Watch Zuko’s expression:
Zuko has been in other fights before. But faced with the same trauma that scarred him again, he is terrified.
He regains control of the fight in a matter of seconds.
His attacks are vicious and unrelenting.
He is seriously contemplating killing Zhao.
This is not normal behavior for Zuko; he doesn’t try to kill other people he fights with (like Sokka during the first two episodes). But Zhao was there during the first Agni Kai; he knows what happened, and he knows exactly how. Trying to duplicate Ozai’s behavior toward Zuko was a mistake that cost Zhao the fight, and almost cost him everything. This is Zuko’s instinctive response to the trauma he carries with him, every day.