I suspect it was more trying to give you good service, and an ignorance with the actual rule related to this very specific, very rare type of fare. To him, you would just be another full fare J passenger, and as a special service, he adjusted the final segment to get you to YUL rather than YOW. The problem might come from AC's audit department, if they have flagged your file to ensure you met all the rules of the fare. You could still receive a call from them advising you were not entitled to get to YUL on that fare, and so they are recalculating your return portion. This is not overly likely, but might occure if they really are auditing carefully all MHD tickets issued to ensure the travel has occured are ticketed/ routed. [Don't mean to be a downer, but it might happen...some on this forum are more paranoid about such things than are others.]