There's no time limit as to when it's ok to divulge a major event. If you tagged it once you should have tagged the last one aswell. You didn't though.
If it was me that didn't tag the post you put up, you would be calling me a dickhead on the fact that it would be spoiled for anyone who hasn't yet seen that episode. And that reveal was far more major. A complete story changer.
Anyway I've no more to say. As you say it's a little thing. Just saying you did the same thing but when you do it, it seems to not be dickhead territory at all. Funny that!