I find that kind of odd, really...
How did he manage a 1500 chakra jump?
maybe from trying to fight Lizard freak, or from training. If you take into account that a standard chuunin has 10k chakra, it's not that big of a jump for a genin.
I thought about all that and figured maybe as well. I'm probably just letting it get to me because Takashi is still at 0. *shrugs* Thought by now Tak would have something. heh Oh well.