Advice please

I went to a 3D/ultrasound place to see how my LO looks at 32 weeks. I was very happy until the tech told me she was measuring a week behind. According to glow app the baby weighs around 3.8 pounds and the Tech said she was 3 pounds and 10 ounces. Should I worry about her measuring a week late ? And how is she a week behind but at the right weight? Please help.