Due date change

So today I went for my repeat sonogram because last weeks sonogram they didn't get a clear shot of the kidneys. so today I was wondering why the the guy kept asking me what my due date was and I repeat it like several time..then something in me said ask why and I did. He told me that my baby is measuring a week ahead of what I am suppose to be,I went from 16w4d to 17w3d. The lady who did my sonogram last week knew this but was like tell ur doctor that we keeping your due date at Nov 10 when its now Nov 4.. Has this ever happen to anyone??