A week or so ago there were National news press photos of GWB tripping while going down on the stairs of Air Force One. [I can't find the link to the photoset that I thought I saved.]
Below is an animated gif of Bush going down the AF1 stairs. I've exited from planes with stairs and I normally don't clutch the handrails because I can walk without assistance (plus I'm carrying stuff). Below we see Bush clutching at both hand rails (first frame) and then he holds on to one for dear life until he regains his balance.
My guess is that he is drunk or missing some mental capacity that would let him walk down stairs without needing handrails.