I'm sure the glider had shrunk since I last clambered aboard
Funny that. I noticed the same thing a couple of years ago when I flew in an aircraft that I had flown once before, over 40 years ago. I complained to a friend that the cockpit had shrunk and he charitably suggested that I was in a 7/8 scale Vampire!
The Vampire's owner refers to it as a '250 kt wooden motorglider'.