20 week anatomy scan follow up

Hi ladies!

So I had my anatomy scan yesterday and the doctor said everything looks great, yet I need to go back in because my little girl wasn't in a certain position. I understand that she wasn't in a certain position, but if everything looks great then why am I going back? Do doctors need to check off like a list of positions/measurements that they have to get in case of a lawsuit or something? It wasn't made clear to me what they were missing, so I go back in two weeks. Thanks ladies!