Grandfriends

It was Grandparents and Grandfriends Day today. Am I the only one puzzled by "grandfriends"? It's not in the dictionary, though it's certainly snappier than "Grandparents and Much Much Older People Who Aren't Related to You Day." Is this a common thing? I don't get out much, but I don't know anybody who has a friend more than, say, 20 years older than them. I'm around 40 years older than most of my students. Does that make me a grandfriend? (Just as an aside, I keep typing "grandfiend" by mistake) I don't have any kind of problem with the concept, I just think if I were trying to expand the potential target for an event, this wouldn't have been the first thing I picked.