I actually have had the same thing with my recent babies, the very last one out has been taking forever to suck what's left of his umbilical back up. He still had a little nub of it, and he was so active (even though we separated him) that he apparently rubbed it back OUT.
Since then my boyfriend tied off the extra and cut very close to his belly, added neosporin just in case, and he's been looking fine. But of course, I'm paranoid he'll never pull the tiny bit of what's left back in there.
Will that also just dry up and fall off or should I be worried? (This is my first clutch and all the other babies haven't had the issue)