I would give her a handful of hay and see what she does with it. Most rabbits will play with hay, but the only ones I have ever seen gather up a big mouthful and carry it around were nest-making does. I have had a few that didn't make a nest at all until just minutes before the babies arrive, but most will start nest-making several days before then; they often dig in a corner of the cage as if digging a burrow, too.
Of course, it's possible that you just have a rabbit with a cranky personality, too. I have had a few like that; even some that would attack anyone that dared to put a body part into their cage. Since the normal gestation on a rabbit is about 31 days (give or take a couple), you should know one way or the other within a few days.