What has changed of course is now he isn't trying to be funny, but he still sees the AD things he does as funny, and I suspect when he makes me laugh he likes it!
So in some small way, and this probably sounds a bit weird, my supspicion that dad is enjoying making me laugh, is me clinging on to the hope that he still worries that I may be upset or sad.
Zoe, I'm sure you're right. Your dad is still trying to make you happy.
What a lovely man he sounds to be, and what a wonderful relationship you have with him.