Eureka -- I figured out the weird sprite! Even though it's an old version of 59, it's also used in the game as 65-stone. You used 65- and 5-stone in your deck to solve a puzzle, then went back to beat the tutorial. No glitch involved!
[I somehow missed this when looking at the spritesheet, I only noticed when watching the posted video where the player accidentally made 65 while deckbuilding!]