It actually looks like it is. I can't think of anything else it would be.
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Yeshua77 commented
Actually if you check the few frames where it appears 1 at a time you can see that it behave like a nip would, also it's not a shadow and it's not part of her other hand because there is a frame where the hand move and yet the nip tip stay still. I'm pretty sure that's the elusive Nigri's nip, if of course you consider such a thin sliver a nip 