Martin Boyle put in successive deliveries from each corner flag during the second half, the latter of which was powered home by the defender on 64 minutes.
However, Glass felt there had been a foul on Dons defender Declan Gallagher during the initial set piece, which wasn’t spotted by referee Alan Muir.
"There’s two corner-kicks in succession and I think there’s a foul on Declan [at the first one],” said the Aberdeen boss and former Hibs midfielder. “We’re getting watched for blocking at the other end like a hawk, but at that end of the pitch it’s all right to knock Declan over and it not be a free-kick.
“It’s not what cost us the goal because Declan lost his man at the second one, which is disappointing.”
Glass felt a draw would’ve been a more deserved result from the contest, which saw Shaun Maloney pick up a victory in his first match as manager.
“I felt like we looked comfortable in terms of not conceding a goal in the first half, but I wasn't happy with how comfortable they looked on the ball and I thought we could affect that with a change,” he said. “I think it showed that at the start of the second half but then the game got really scrappy.
“Neither team did enough to win the game, for me, except from the set-piece. From open play it was looking like a 0-0.”