Dr B can not tell you because he can not examine your bird.
Your bird could be stimulating himself or herself, or there could be something wrong. Only an in person visit to the vet would tell you.
Lots of birds do this, so I suspect all is fine. The problem is, none of us live with your bird, and there might be other symptoms that would lead us to believe your bird is sick.
Birds should see an avian vet once a year, so if your bird has not been seen by an avian vet, then now might be a good time for a visit.