Baby not cooperative during 20 weeks scan??

I went for my 20 week anatomy ultrasound last week and baby did not want to cooperate to get all the proper measurements and to look at everything they needed to see. We did find out the gender (it’s a girl!! Woohoo!!!) but the ultrasound tech said we would need to come back in a few weeks to try again. My doctor didn’t seem concerned at all and actually pushed the anatomy scan back to the third trimester. Has anyone else had this happen? Should I push to have a rescan earlier? Regardless of the scan findings, we would choose to love and cherish our baby girl, I’m just curious on other mamas thoughts.