Some people get, either in addition to or instead of, pimples on the scalp rather than scaling or dandruff. Technically, this is folliculitis rather than seborrheic dermatitis. Cause is not known, though stress plays a role, in my experience. I wouldn't call them normal, but they aren't serious. I advise you not to pick at them, and to show them to a doctor for proper diagnosis and appropriate treatment.
Take care.
Dr. Rockoff