You said: "There was a point in my life where I would have been supremely pissed at this guy. I would have pointed out that I wasn't that sweet, so just get me the drink and lose the patriarchal bullshit."
Apparently you're not from around here. The term "sweetheart" carries no such offensive connotation in these parts. I call my grandmother that all the time, and she's a tough cookie who would not hesitate to smack me one if I got too cute and forgot to be polite with her. In California at least, "sweetheart" is a completely respectful form of cordial address. It might be a bit questionable coming from, say, a bank teller, but a bar is informal enough to allow its use without undue familiarity. Besides, if someone thinks you're sweet, how can that be a bad thing even if they're mistaken?