Try not to panic!

I was told the same thing at my scans, by saying above average they just mean your baby will probably end up slightly bigger. The average in the U.K atleast is 7.5 lbs although I hear of babies all the time that are over that! and if your family are tall its highly likely your going to have a longer baby!
I was told not to read to much into it though! all babies grow at different rates, some babies grow alot then slow down where others go the other way and some just grow and grow and grow!! Personally I think mine has slowed down alittle but I will ask more at my appt on friday!
Just ask at your following antenatels whether the baby still seems to be big, and as I said try not to worry as 'above average' doesnt have to mean huge!!