Yes, he showed he was human and hit Lemieux when he was down and threw a punch after the bell. Those are not flaws though, not in my opinion. Slightly out of control aggression is not a flaw for a fighter.
He has a killer jab (could have beaten Lemieux with that alone), has good power in either hand, cuts off the ring well, is aggressive with constant pressure, and is always in position to throw something that is intended to hurt. His defense is great too, along with that jab he has good head movement, good footwork, and always knows where he is in the ring. Did I mention he is aggressive as hell which adds to his defense. LOL
Lemieux is not a great boxer which made GGG look great instead of just very good. What are GGG's flaws? How would he look against Cotto or Canelo?