Maybe it's because this guy was practically winning without even using his curse seal and now Neji isn't in a position to do much to him (last page of 196 notwithstanding)

Without Kyubi Neji had effectively sealed up that fight Naruto couldn't touch him and Neji could destroy him at his leisure.

He's in the same situation that Naruto was that would make his new opponent far tougher than Naruto.

This isn't a sudden burst of power Kidoumaru has Neji scouted.