Cool reference Katherine.
The way I see it, the initial encounter is meant to appear like very typical and slightly competitive cowboy posturing (by each of them... but yes, more so by Jack) and "sizing up". But just below the surface is the flirting... a kind of flirting that many audiences probably wouldn't be used to looking for. Subtle cowboy-flirting is not the same thing as filirting in a romantic comedy, etc. This reminds me of the old questions about when the attraction started for both Jack and Ennis (and whether it was from this first scene). Perhaps their indications of interest are so subtle (especially from Ennis's side of things) that many people wouldn't even register what's happening (or what might be happening). They (and again, especially Ennis) probably feel they have to be super subtle and circumspect due to a level of confusion/ naivete and all the fears that come out through the course of the film.
