I've noticed this, too. I work with a university Women's Glee Club as part of my assistantship and have found that they almost ALWAYS refer to each other as "girls". I think for them, and for many younger and college age women, it is a term of endearment...a bonding thing. They also embrace "women", but don't use that term as often when addressing each other.
In rehearsal situations, I almost always address the women in my groups (regardless of age...from grade school to my adult choir) and "ladies" and the men as "gentlemen". Of course, someone in the tenor section will usually raise his hand and ask if I want them to sing, too, since I only asked for the "gentlemen".![]()