If not about the topic of the conversation, could it have been about word choice? Not even so much jargon, but if they include words that might be in general use, but get used in a particular way by creative writers.
I haven’t had the experience described in the quote, at least not that I’ve noticed. Partly because in casual conversation with people I don’t know, I mostly don’t find out what they do, either for a living or as hobbies.