I found this concerning too, until I watched the beginning again. He was chewing on his lip during the intro, and they might have done a few takes of that shot. He says superbowl perfectly fine at 8:11
That makes sense. His teeth look a lot better than they did back in the day, I was wondering why. I mean, does a 50yo man get braces done no matter how much money he has? Would it even work? Probably not.
I immediately recognized it as the same thing my dad did for awhile after he got his. Dentures lower the roof of your mouth a bit, so you have to get used to it and your mouth still tries to fall back on muscle memory for awhile, so you get weird sounding S's.