Yeah, Pelota has that too. I think it's from their umbilical cord thingy. Don't they have to sit in the egg when they hatch and "soak up" the rest of the insides of the egg or something? Maybe that has something to do with it. But yeah, I think that's normal. I'm sure I've seen it on Pelota previously.
We need an expert to give us a definite answer. ;)