If your doctor didn't see any brain anomolies, I don't think you should worry at all.
Some people have bigger heads than other people - that's why there are so many hat sizes for me. ;D
I think this is much better than the head measuring small, really.
No it fine I a mum of 2 soon to b 3 and my first head always measured bigger but was normal by birth check with ur doc if u r worried but I sure all is fine xx