I think your tummy muscles finally gave some, that's what happened to me, one day it was hardly anything then one day, BAM there it was! That's so exciting! Congrats!!!
Yea, they've been trying hard to hang tight but are losing the battle:) I can definitley feel them stretching and complaining!
You look really good pregnant, I know what you mean about the stretching and complaining my belly was sore as if I had done ab exercises. I love baby bellies! Soon you'll be able to see (and feel!) elbows, knees and feet pushing out! Meara was a butt and head gal, she was always shifting positions, one min. my belly would be relatively small for being PG and the next she would shift so that her butt her head was pushing out and my belly would grow... so cool! Maybe that's what happened within those three days and that's why you "popped" lol I found that term amusing!