She's being aggressive, but she doesn't mean it like a rooster would. She is letting you know she trusts you and wants to be touched and handled by you. She's letting you know she has decided to "own" you. When she beaks you, it's meant to get your attention, not as a sign she's miffed with you. Chickens can only communicate touch by using their beaks. If you'd observe, hens will beak each other to keep the lesser status chickens in line, as well as using their beaks gently with each other during preening.
In hens, this behavior is beneficial, and I never discourage it. It means you're an accepted member of the flock. I have quite a few like your girl. Next time she signals to you with her beak that she wants to be touched, pick her up and tuck her gently in the crook of your arm. Sit quietly, and soon you'll see her eyes close in contented satisfaction.
When I have the time, I like to indulge in group hugs. I get down on my knees, bend over, open my arms, and the hens will move in close for hugs. I'll feel a pecking on my back, turn around, and there is a hen who feels left out. I reach around and include her in the group, and everyone is so content, when I back away, they're all still in a tight formation just like a racked bunch of cue balls. Good times. Today I had a record six-hen group hug.
