Yet while referee Mike Dean reached for his pocket, it was not the former Manchester United player he had in mind but rather West Brom striker Shane Long.
Dean thought Long guilty of diving, continuing a run of controversial bookings for players going down under contact. Fernando Torres and Danny Rose have had yellows in similar incidents this season, suggesting that referees are returning to the days when they used their judgement to decide the ferocity of a challenge rather than merely try to decide whether any slight contact was made. Football is, after all, a contact sport.
But did O'Shea's reaction betray a guilty conscience? Did he think he deserved an early bath? Either way, it made little difference to his side: the Black Cats lost 4-2 after a thrilling finish to the match, the result sending West Brom to the nosebleed-inducing altitude of third in the Premier League.
Should O'Shea have seen red? Watch his confused reaction in the video above (UK users only) and have your say in the comments box below.