Thanks, orangetruck.
And thanks also, atalley. You know, I do agree that a large part of Jack's clumsiness in that scene had to do with his being distracted by Ennis stripping in front of him. In fact, I think this also explains why in the next scene, I also feel on edge. We see Jack peeling potatos, while trying to look clam as Ennis washes himself in the background. I get the feeling that he might cut himself accidentally, because it was clear that his mind was focused elsewhere.