I'm much less polite than you. I like to whip out my pen unsheath the needle and if people have a phobia, well watch them faint.... Sport I think it's called, much like introducing large spiders to tables where there are persons with Arachnophobia!I concur, lucky escape for you. I don't think it's a problem if someone is scared of needles, or uncomfortable around them, but if they were rude enough to make a scene and say "eww" that's not the kind of person I want to know.
I think @Postitnote is right though, and consideration works both ways. I do my insulin at the table and usually can do it without anyone seeing. But if this isn't avoidable, like maybe a circular table where the person next to me can see my stomach, I would warn them that I have to have an injection so that they can look away if they don't want to see it. My experience is that most people are fascinated and want to watch
. Im bugg@red if I will slope off to the loo to test and or inject, and don't actually carry a head vice to force people to watch 
I did have one "friend" who did the whole drama queen thing, at the one and only time I injected in front of her , which I found a bit rich as previously I had sat and held her hand during a breast biopsy 
. Once I pointed out that for me it was an essential thing I needed to do, multiple times daily to stay alive and well, and I was not actually waving the needle at her or have at HER like Vlad the Impaler, she stopped being such a prat
I find it's usually an educational opportunity without preaching at people. Often the conversation heads that way long before the meter/ injection bit starts, as people comment on or ask about my dietary choices ( low carb, coeliac )
The most frequent comment I get is "but you're not fat"
