My baby was over 95th centile until my 35 week growth scan where they've dropped to 60th. There's always a margin of error with the scans anyway, but also lots of babies bounce around a little bit with their growth. It's still early days yet.
Normal, your doctor will be measuring your tummy at every appt, you can always ask for another ultrasound closer to your due date. They might just not want you to go past 41 weeks, like with my baby. I was at 35 weeks and my son was measuring 6lbs 10oz, he came out at 40 5 days at 9.5lbs. but they can tell how much room your baby has and how much fluid is in there. Those measurements have a margin of error going both directions.
If they aren’t worried then I wouldn’t be either. My daughter was born at 36+4 weeks and weighed 5lbs 5oz x