It's not because she's slower; Ellie can't seem to keep up anymore, because of their power in numbers. They can be a force to reckon with. They've even managed to share some major milestones. Gavin lost his very last baby tooth, on the same day that Benett lost his very first. It was exciting for both of them... and each of them individually.
Like many things that Gavin does, he lost his tooth completely on his own. Letting us know, almost as if it were an after thought. "Oh yeah, I lost my tooth. I guess I can get my braces now..."
While Benett's experience was a very typical, theatrically-dramatic event involving an aggressive game of catch, with a baseball. You know, the kind of game where one uses one's chin to stop the ball. Accounts differ, but the end result was a lovely note and a tiny pearl for the Tooth Fairy.
At first, I worried that we wouldn't be able to make each of their moments special... maybe that's how twins feel about sharing a birthday... but in the end, I guess it was special, because they got to do it together. And it was proof to me that there is no need to "make" anything special, because when it is, it just is.