The “strong possibility” of a school bus strike that the city raised the alarm about back in November hasn’t come to pass. But it has still caused a headache at the Department of Education.

A message sent to principals last week noted that MetroCards distributed to schools at the time were being used, even though they were meant to be handed out only in the case of a bus strike.

Those MetroCards were disabled last week and the city asked principals, perhaps quixotically, to collect the ones that had already made their way into circulation.

“If you find that the MetroCards delivered in these packages were inadvertently distributed, please collect them immediately,” read the note tucked into the Principals Weekly newsletter.

The message was very different in tone from the alarmed dispatches sent to principals — three times, one principal told GothamSchools — the day Mayor Bloomberg held a hastily planned press conference to announce the strike threat. At the time, city officials said the union that represents bus drivers had threatened to strike immediately, a charge that union officials disputed. They said the union had raised the possibility of a strike — as it had repeatedly in recent years, without action — but not set a timeline.