Repeat ultrasound after anatomy scan?

Serena

This is my 3rd baby and I was with a different doctors office for my first 2 babies and after the anatomy scan that was it until 36 weeks but now I’m in a new office and my anatomy scan was literally ten mins long and the tech said the measurements looked good but to reschedule another scan in 4 weeks. Is this normal routine? Or is this because they saw something on the ultrasound? The doctor still has to review it but now I’m stressing out! My other anatomy scans lasted 30-1 hr and find it odd since this was a ten min thing.

She said she got everything she needed so this definitely has nothing to do with the position the baby was in so I’m lost.