35 weeks 2 days and doctor requested another ultrasound

Did any of you ladies had to do another ultrasound around this time? The doctor said it is only to check the baby’s growth. However, I already had an ultrasound done when I was 31 wks 5 days to check if the brain cyst detected in baby had gone. Thankfully the cyst had gone but just wondering why another ultrasound again bcoz at 31 wks 5 days baby was 4lbs 6oz(in the 52nd percentile). Is it a common thing to do around the 36th week mark?? Baby is head down already as confirmed by doctor.