The first time that happened to me I went on a small rant about some minor health issues and the state of the world in general and that settled the conversation

The first time that happened to me I went on a small rant about some minor health issues and the state of the world in general and that settled the conversation with an overseas colleague. It was later that I found out that "how are you" is a perfectly valid answer to "how are you" and it still boggles my mind 20 years later.