Although ultra appreciative of the philosophical anecdote, Deleuze apparently did not know about Unamuno.
Unamuno was an inveterate folder of paper. Here's an anecdote from one of his obituaries:
In the course of a visit that Andre Corthis made to Unamuno in Salamanca, she saw, perched on the edge of the bottle of ink on his desk, a vulture made of paper that was so finely folded with such delicate art that she couldn't withhold her admiration.
"I made that," he said.
And Miguel de Unamuno explained that he had a mania for folding things, it was his favorite distraction. While siting in his chair giving his courses, his fingers never ceased making little objects or animals out of paper. A science that he humorously called cocotology."
I like to think that Unamuno, the committed anti-fascist, the man who was expelled from Spain in a military plane under one dictator and who denouced Franco at the end of his life, made a specialty of folding small bits of paper. There is something very... sweet about that. I would like to think that Paul Valery had, as well, some very cute nervous tic.