It's a bud, and it's not as weird and uncommon as you might think! I've had that happen, and know of at least 2 other people that experienced the same thing with their keikis. You can leave it on, it won't affect the growth of the keiki in any way. Here's a photo of what mine looked like in bloom.
cool! i had no idea they could do that! must be happy then thanks so much for posting and for the pic.