By Whitney Pastorek
Updated August 19, 2009 at 09:25 PM EDT

Oops! The upcoming third episode of AMC’s critically acclaimedMad Men was briefly available on Tuesday night to iTunes users who’d purchased a season pass for the series, the Associated Press reports. AMC is investigating how the leak occurred, and has asked anyone who did receive the episode to avoid dispensing spoilers until after the episode’s scheduled airdate of Aug. 30.