Do snakes become more nervous, or flighty before they shed?

Yes. She can't see very well and even if she knows it's you, she's seeing a blob coming at her as opposed to your hand. She's also a bit uncomfortable and irritable right now. I'd recommend leaving her be until after she's shed. You've done a good deal of handling so far, so once she's shed she'll be back to normal and you can resume the handling.