He had been quite pleased when he watched the confrontation from the shadows, Weasley had been injured by the chess game, leaving it to be just Quirrell and Potter in the final dungeon room. Quirrell had done his part perfectly, ranting about Voldemort, using phrases Dumbledore had heard Tom use in Hogwarts, and on the battlefields. Henry even retrieved the Stone from the mirror. It was perfect. They had a quick scuffle where Quirrell knocked Potter out and Dumbledore stepped in, killing Quirrell now he wasn’t needed. Using Fiendfyre to destroy the body and evidence before he finally took both Potter and Weasley back to the infirmary. He spun the flawless story of how when Quirrell grabbed poor Henry, he burned into ash, how Henry saved the Stone from Voldemort and how he, in turn, saved Henry. But when he had gotten the stone back from the boy, he had been horrified to discover it was a well made fake. He had no leads as to who had the real stone. It couldn’t have been Henry, he wasn’t smart enough to create a fake and then hide the original, let alone hide his thoughts about doing so.