I remember worrying about that, and even running a panel on it at an AI conference but I didn't remember inventing the term. The next day, as luck would have it, I found myself sitting in a small office with Marvin Minsky (and others). I asked him who invented the term AI Winter and he had no idea. We began to discuss the events of those days and the fallout from AI investments at that time and had fairly different views of what had happened.
All this reminded me of the column I posted here a couple of months back about Lamar Alexander and his insistence on making kids learn history. History is very nice as long as it is true. I wonder how he knows what is true.