September baby may become October baby!?

I had my appointment today to get the results on my sugar glucose test and my doctor measured my daughter at 28 weeks instead of 31. He had me go down to the labs to run blood work and to return in 2 weeks. Hopefully then to discuss whether or not I'll be having her on my original due date or later and to set up a ultrasound. Has anyone else measured behind and still delivered on their original said due date? This is my third pregnancy and first baby that has not measured on time.