[EDIT] Did you have an elective c-section/induction?
I had an induction at 41+1 and wonder if I should have waited...but I know waiting too long can be risky. He was born at 8lb 10oz and 21.5 inches with no delivery interventions except epi.
I know someone who had an elective c-section at 37 weeks and there was no convincing her otherwise.
EDIT:Those of you saying you know when you conceived..thats not true. You dont know when you ovulated and even if you did...you dont know when fertilization and implantation took place...you could still be off by up to 2 weeks. :)