Well, he also didn't give a smidgen of a clue last year that he'd already shot his character's death...

Also, they seem to be keeping a tighter lid on spoilers this season. Besides the massive spoiler dump we got over the summer, we haven't heard that much else. No one expected Misha again after 6.03 becuase he hadn't been listed and the summaries didn't mention Cas, and they didn't put Mark's name in the credits this episode.