I have always steered clear of Facebook, but as you know I have been to a lot of bars and clubs dressed, and what you are experiencing is along the same lines as what I experience in person. A number of women have asked about following me on Facebook and instagram etc, or even wanted my phone number. This would never happen to me in drab mode. Add to that all the other interaction I experienced like dancing. It is a completely different experience. Probably the most awesome example I posted about some time ago was when 3 young women escorted me to my hotel when I had too much to drink. That blew me away.
Some reason It is just a lot easier and seemingly natural to become friends with other women when we present as women. And like you noticed - they often seek us out rather than the other way around. I have been really baffled by how the social dynamics are altered when I go out dressed. It is no fluke though. After almost 6 years of doing this, I understand what you are talking about, but it is certainly hard to comprehend why things work this way just by changing our clothes and adding some makeup.
But I do love it ; )
Sandi