Why interfering and not letting your kid develop his own ways? Answering "How are you?" in detail sounds to me as a fantastic trait of his personality.

When I was 7-years old I stopped calling my parents mom and dad and switched over to calling them by their names. I just couldn't understand the logic of other people call them one thing and me calling the something else. Happily nobody tried to "correct" me according to social rules, and still today it wouldn't cross my mind to call my mother 'mother'!