For example it's fun to hear Steve Eley mention the release of the fourth 'George R. R. Martin book', obviously people didn't refer to the whole series back in 2005 as Game of Thrones.
I think they might have? It's not uncommon to refer to a series by the name of the first book, especially if the book name is more catchy than the series name. "Song of Ice and Fire" doesn't stick in my head or describe the series as well as "Game of Thrones" does. Similarly "The Golden Compass" in place of "His Dark Materials" (though that one is more confusing because I think it had a different first book name in other countries).