Just be patient till the real problem reveals itself. You can ask her whats bothering her but if you had that type of relation ship you would not be divorced. more than likely she's just simply miserable. and misery loves company.
I must say though you will have to find a way to creatively respond to it. for ignoring it will only make it worse. try and figure out what it is, even if you have no proper response to it, at least you will know why she is doing it. Which may be helpful later.