Here be probable Madoka Magica spoilers
[The stuffed animal-like being is not a welcome sight to this girl, but the irony of a prison being able to catch and arrest the being who has trapped her in this fate is not beyond her.
Without it there to grant Madoka Kaname's wish, there's no way for her to be trapped in fate as this girl is. Perhaps Walpurgis Night would never actually be born without the Incubator there to hatch it. But the doubt still remains whether that would be true, and thus her expression remains cold and aloof as ever.]