I have heard it happening before with people who were just tired or worn out. That part of this story never bothered me much.
Every President has bad moments like that. How the media chooses to treat it is always different. Biden just has more of them than most.
Back in the day when
Saturday Night Live was still occasionally funny, they spent a lot of time lampooning Gerald Ford for his clumsiness.
And of course when Trump walked down a slick ramp slowly, the media talked about it for weeks, speculating about everything from inebriation to some neurological illness.