why

What has been seen cannot be unseen

Long may he reign

I don't think he liked the film, but one of the things it could be is that he was worn down from the premiere? I read that he participated in some sort of panel for about an hour after the film had ended. It might also be easier for him to breath with his mouth open like that, he was in a wreck back during TESB or ANH where some of his nose needed replacement so some of that "shocked look" could just be him breathing in the easiest way for himself.

I've come to see Mark as a pretty sporting person who always tries to find something positive to say (even about the things he disagrees with) so I don't really know. I want to give Mark Hamill a hug regardless!

Looks like someone had a "chat" with him.

I realise what Chris was saying was on point and the star wars fandom is just that, but do we have to apply the usual nitpicking irl too?

Maybe he isn't overly happy with the way things went, maybe not. Maybe he was genuinely sad at the ending, maybe he was just tired on the run up to the premiere,
or maybe he remembered he forgot to turn the oven off back home. Give the dude a break without having to politicise hearsay.

Good to know. Must've been upset about something else. I'll check the timing but it could have to do with Carrie Fisher's passing, they were quite close.