6mo pulling her hair !

Hello ladies, so yesterday we were getting little one to nap and she woke up twice from this crying and screaming. We decided to head upstairs with her, daddy was upstairs while I was downstairs washing the bottles and she was still screaming and crying. When I came back upstairs daddy told me she was pulling her hair! She’s been having a feel of her hair lately but has never pulled it even while upset! Is this normal? Help!