As a belated follow-up, it turns out that this wasn't a delay in posting by Air Canada -- it was a failure to post at all. I've requested retroactive credit for the flight. My MP number was on the ticket, I got credit for the other segments, but for whatever reason that segment didn't post. It is kind of funny that the only segment I remember not posting in the past five years was the exact segment I needed to cross into elite status. I hit premier officially on the return flights, so the wait while they manually post the lost segment isn't a big deal.

I do wonder how many times a segment doesn't post and because it isn't that important, the member doesn't even notice. I don't know that I would have noticed this missing segment if it wasn't the exact segment I needed to hit 30.