I would guess this would happen if the client’s clock is wrong, set to the future.
It might also be that the actions “Start Time” was over 7 days ago, but it showed up just now, so it was overdue already. That said, I’m not sure that the action “Start Time” is what dictates the start of the 7 day time frame, I would expect that to be based upon when the machine first gets the action, which if offline until this appeared, would have been just when it was turned on and synced. It is also possible the system got the action, but then was turned off, so it came up overdue.
@AlanM or someone else may be able to shed some light on what the deadline counts down from.