Ultrasound weight of baby

I've heard a ton of stories about "they said my baby was 10 lbs and he came out 7!" And not to believe the ultrasound weight predictions because they're hardly ever right, but are they always over? I'm 38 weeks and my baby is measuring 6lbs5oz and in the 30th percentile. Everyone keeps saying don't worry they're never right and that's what's worrying me! I'm afraid she's gonna come out 5 lbs or something. I've never heard of the baby weighing MORE then the ultrasound said..?