It might be a stage, or it might persist. It could be helpful to point it out to her away from her
complaining (take her out for a soda and tell her there's something you want to discuss with her). It is often amazing to me how people get into habits like this and never even realize they're doing it. Also, point out how it makes you feel when she does it, rather than arguing about the content of it. Ask her if she'd be willing to work on it.