Noni.. im not too sure as why youd need to have a scan. My only thoughts is with the fundal height, amniotic fluid could be a big influence on size also, whether you have a lot or not.. so they may just want to double check whether youre all ok to go for a natural birth.
Jesse fundal height was always 1 week ahead and he was quite big when born 8lb 9oz.. i didnt expect him to be that big.
But just think of it like this, you get to see bubs again!!!