Remember when sasuke fought danzo, then afterwards wen into a quick battle with naruto, sakura and kakashi. . .i don't remember clearly i think it was either naruto or kakashi when sasuke had gotten angry his susano'O change it's form yet again but he was weak from all the previous battle he had the day and was loosing the light in his eye so he didn't use it, do you think maybe just maybe he unlock the perfect form of susan'o right there???