It doesn’t really seem like humorous hyperbole, though. It’s currently just factually incorrect. And it’s in your power to fix it, especially if you agree now in retrospect!
I am not a native speaker, so my interpretation might be wrong, but I tried to evoke the semi-serious but good-natured "You went to the bakery? You better brought me a snack as well!" meaning with "better have", not the "must have" meaning.