stomping the foot and shaking her head is a half-hearted threat gesture . It's her expressing her irritation at being asked to leave good grass. Why should she? I mean, she is not on any schedule. she's got her sensitive nose down in fresh grass. Can you imagine how enticing that is?
So, yes, I would address that expression of bad humor. Not like a punishment, but do something big enough to break her out of that thought. I might stomp the ground loudly and hiss at her loudly. and if she jumps back, that's fine. It's about waking her up. Then, move her on to another good place of grass, and let her eat.
If you are going to hand graze, get your horse good and used to being interrupted to move a bit further, then allowed to graze, then interrupted, and on . . etc. This way they know that you aren't stopping the grass, just shifting. The will not worry so much every time you ask them to move away from some place they want to be at.