Baby measuring big at 31 Weeks! Anyone else?

Kelsey • Due 19/01/15 with a baby boy ❤️
I just got back from my 31 week doctors appointment. So far my pregnancy has been great! I have passed all my tests, blood work, pee samples etc. However, I am 31 weeks and baby Liam is measuring at 34 1/2. Doctor is scheduling me for an ultrasound to check his growth. Anyone else measuring big? Any problems or did you just have a big healthy baby? I know my due date is pretty much spot on considering I know the last date of my period so he is definitely 31 weeks and measuring large. Thanks!