It's an individual matter and depends on lots of things!
If a girl calls me baby and she be my friend, my girlfriend won't do anything, she's my friend and it's just a kind word and would be appropriate in our world.
But if a girl calls me baby and she's a stranger, my girlfriend trusts me pretty well, but if we do anything or not! It would depends on the situation and the tune. However if it sound inappropriate my girlfriend will kick the girl before i decide anything, cause she owns me!
You cannot control what others do or say. What you can do is watch how your boyfriend reacts. As long as he doesn't encourage the other girl, you do nothing. If he does encourage her, then you have a chat about what you consider is appropriate behavior. If he agrees and adjusts things will be good. If not break up and move on.
If she's a waitress/server ... You realize she's working him to get a better tip.
lol