I'm not quite sure, ever since Wintertusk I've always been sort of wary of my levels, I don't want to be wasting tons of xp when it comes to Khrysalis, or even Azteca.
Re: Is level 64 bad if I'm still in Science Center?
You'll reach 100 somewhere during the first half of Khrysalis. Unless you manage to get there before they release the next world, I woudn't worry about it much.
Re: Is level 64 bad if I'm still in Science Center?
Nope, you're fine. That's about normal. Finishing CL between 65 - 70 helps you survive higher worlds. You are going to reach max level before the end of the game no matter what you do, so take the sides and be strong now.