Originally posted by: AssertnFailure
neji-aniki: the reason people were surprised was that

1) naruto was giving off an immense amount of chakra....even kakashi and zabuza could sense the demon fox's influence and neither of them have byakugan.....hiashi already knew that naruto had the demon fox 12 years ago, anyway...just like all the other adults

2) hiashi and neji were all surprised because naruto was able to bring out chakra after the 64 hands of hakke was used on him.....im sure if neji figured it out, they wouldve made that clear
Kakashi said that the byakugan could see the chacra circulatory system. So, as the pic shows, that's probably what they saw, that red chakra. Hiashi knew it was from the kyuubi, he said something to the effect of *Could that be..." one can assume that he, knowing the kyuubi story due to his age, thought could that be the kyuubi/the kyuubi chacra.
Besides there's a shot, that I won't screencap but is there, where the fire-like chacra transforms itself in the image of the kyuubi. If Neji could go so far as seeing the chacra path, it's likely IMO, that he also saw that image of the kyuubi. I don't think he *knew* it was the kyuubi, though. But likely, Hiashi did.