I don't think you're wrong. I can understand feeling disrespected when someone who isn't aware of your situation hits on your husband, since he presents publicly as "taken". It may help to keep in mind, though, that there's a chance (however small) that these women are aware of poly and are checking to see if your husband is or would be open to it as well. Unless you're ONLY going to date within the "out" poly community, you sometimes have to broach the subject with those who appear taken! (Respectfully, of course. I understand that's probably not the case most of the time for you and him, but maybe it would help you to give the other women the benefit of the doubt.)
For me, MC getting hit on by others doesn't trigger jealousy. It triggers amusement, because 1) he almost NEVER realizes he's being hit on. He's rather oblivious, to the point where you pretty much have to kiss him for him clue in. And 2) I snicker (unkindly, I'll admit) at how a random stranger hitting on MC has NO CLUE what they'd would actually be in for. Yeah, he might be interested in dating them. And along with that would come me and TGIB, and our kids, and...yeah. Hardly a stereotypical "I'm dating and/or sleeping with a married man" arrangement! So, perhaps trying to keep a sense of humor about the whole thing would help your jealousy?
It's not a fun feeling, especially when you know it's a little ridiculous. I wish you luck in trying to move past it! I think you're already on a good path since you sound like you know it's silly and aren't asking your hubby to change his behavior to help you feel better. But don't beat yourself up over it either! Feelings happen. You're doing what you can to recognize the triggers so you can more effectively deal with it, and that's about all you can do!
Pan Female, Hinge in a V between my mono (straight) husband, Monochrome and my poly (pan) partner, ThatGuyInBlack