Pip contacting my gp

I am claiming pip due to my sciatica and anxiety. I did not give much evidence just a supporting letter from my mother saying how much she cares for me.

I have had my telephone assessment and received a text a couple weeks later saying I had been awarded. I rang dwp and they told me what I had been awarded and how much back pay I was getting. It'd been a week and a half and still no back pay received. I rang dwp up and they said they are waiting for my gp to respond.

Should I be worried? Why would they award me pip but now not give it and say they are contacting my gp? And wouldn't they contact my gp first before making a decision? I'm just confused by the whole process!