Well, firstly, you have to know that's not true.

I said ALL sorts of things to my own mom growing up. Didn't we all?

Plus, keep in mind Nana is most like not enforcing bedtimes, chores, homework etc. on a day to day basis like I assume you are. So the kid saying things like that would be understandable (but on a superficial level).

If you say something like, "You don't know what she's like" - be glad of it! You wouldn't really want her to, would you?