Did you notice? (possible spoilers)

Well, I guess it because they are in a situation with an enemy that's why he didn't think of attacking her. Instead his mind was focused on how to to destroy James and not focusing on sucking blood.lol. But it's indeed a nice observation.

I think you can dismiss it as the spur of the moment for Jasper. The atmosphere is tense and they're focusing on killing James. I think that's why he didn't waste time on reacting to Bella's cut. In New Moon though, they're it was a good day and as always, Bella's smell is intoxicating to them and they're all focusing on her. I think it's a plus that they're excited for Bella's birthday and you know how sensitive Jasper is to feelings. That's why he could no longer contain his urge when Bella had a paper cut. =)

Never thought of that... but I don't think it's a plot hole. Vampires can hold their breath for long period of time. He might have gone into the ballet studio knowing that Bella was possibly bleeding all over the place and prepared himself, holding his breath and setting himself to the task at hand (dealing with James.). Bella's paper-cut was a bit out of the blue and unexpected.

You're right. Maybe he was caught off guard, but in a movie they should pay more attention. In real life that would be the explanation, but in a movie how can we tell someone is distracted? That scene was so great, Jasper flying around cause Edward just pushed him. That's also after that we see how Carlisle is so "human", a good one :D