It’s not something to worry about. It’s normal bunny behavior. At 4 months old, there is a hormonal component. Although sometimes it means Put me back on the floor, I need to go pee. If it does mean that, and you don’t put her back on the floor, there will be pee in your lap.
For some reason, buns sometimes like to dig in the lap of people they like. It’s good that you made the high-pitched noise. It can be painful if they dig frantically and then proceed to nip. That’s not acceptable. Punishment won’t work, but being put back on the floor repeatedly might work – after many repeats. She will have a bunnitude and and a stubborness par none until she’s spayed though. A doe bun hitting puberty tends not to take no for an answer.
My Bam still digs in my mother’s lap (my mother is his favorite person and he jumps up to sit in her lap, so it’s not a protest), although not so it hurts. She has to have a blankie in her lap when he sits there, because he can sometimes decide to nip her clothes and make holes. They have razor teeth – when they want to.
A bunny can also become angry if you stop petting it before you should. It’s of course the bun that decides when you can stop 