Belly measuring large?

Shea
Ok so I went to dr last week and they measured my belly for the first time and they said it measure 17cm well according to my due date I was only suppose to be 16 wks... Well today my friend scanned me and the baby was measuring 17 wks 2days.. Should I be concerned that my belly was measuring 17wks last week and baby just now measures 17 wks this week?