Genuine AIBU here - I wouldn't want my OH to do this to other women, even if he meant nothing by it (and I'm sure none of the men I mention below mean anything untoward).
Every so often, I'll have one of my friend's partners or a now happily shacked-up ex/male friend privately message me on social media telling me how gorgeous/beautiful/etc. I look in a particular photo (or my photos more generally). I think they are all in very happy relationships and I'm not arrogant enough to think "oh, all these men must fancy me (!!) 
But I was thinking about it the other day after the last incident - I wouldn't be happy if my OH did this to his female friends (well, particularly if they had ever gone on a date or two in the past. I think it would be different if he e.g. did it publicly - commented on a photo or gave my friend a compliment at a party etc.
AIBU to think that I would feel a bit :( if my friend showed me a message my OH had sent her saying "you always look like a model in a magazine in your photos - so beautiful" or similar? But I trust my OH not to cheat on me, or be looking to cheat on me so maybe I'm being overly jealous! I'm just glad he doesn't (as far as I know!!)