Of course, it all depends on the context, and the intention of the speaker.

But, generally speaking, "girl" is meant as "young woman". "Girl" could also be a term of endearment. Since you don't know - and cannot know - the intention of the author, you're projecting your own bias.

Grasping at subtleties of language and getting offended, is usually sign of a weak identity or fragile mind, who sees attacks everywhere.

Just like when I used "female" when talking about a woman, and she got all upset: I replied she was also a mammal and a biped, and all those terms were technically accurate, so what the fuss was all about?

In cases like these, the "sin" is in the eye of the beholder. :-)