Our girl did that to my husband for a while, everytime he stuck his hand in the tank. She grew out of it when I started feeding the tank with a turkey baster, I don't know if it was me, or if she associated the baster (and hand) with food and realized it was not a threat. She's fine when my husband feeds the tank, but NOT if he moves things. The closer he gets to the nem, the more aggressive she becomes. She started this back up when he started messing with her nem! I think she holds it against him! A few weeks ago, she drew blood! She's not even that big yet!
Trying to undo so many millenia of instinct isn't easy!
Good luck!