I measured 10cms, or more at times, ahead during my last pregnancy. After having an u/s (which I didn't really want) to find out if it was twins and seeing only one baby, I decided not to have fundal height measured anymore. I had my DD about 39w4d, she was 8#1oz.
I am measuring ahead this pregnancy as well... Not sure why I keep doing that to myself! LOL! Although, it is always better to be prepared for an early arrival!