What an interesting observation, Lee! I shall definitely look for those details next time I revisit the film.
I admire this scene a lot, too, and, though I note the seriousness of the men's demeanor, do not feel the scene to be the sad, forlorn one that so many see it as. The overriding emotional quality I sense here is mutual respect--these two feel consummately at ease with each other, and have a deep, abiding admiration and understanding of the one beside them.
In the story-to-screenplay publication, incidentally, the two are described in this scene as riding like Randolph Scott and Joel McCrea in the film Ride the High Country (an early and highly regarded Sam Peckinpah Western which I have not seen).