I think it annoyed her at first but appears she gave up trying to get rid of it...
I was watching earlier and I could of sworn that she was looking at the fluff contemplating how to remove it, would stick her beak into her chest feathers and scratch around, wiggle a head a bit, then come back out for air, still white fluff. She would look at it again, do the head shake thing, look at it, turn her beak toward her chest, wiggle it around....come back up for air, still have the little white fluff on her beak!