I am still not sure what the underlying mechanics are.. I would love to hear from you guys.
In your particular situation - False Familiarity
The Gym is a Fishbowl and everyone is consciously aware of everyone else
This
might not be the first time she's ever seen you, just the first time there was some social exchange
If you're killing at the gym, she's seeing you be excellent (Tao of Steve), and that just makes her like you more
So this could be an example of
Quasi-Social Circle or
False Familiarity. We start to like people that we see all the time
But the general situation - Time to Marinate
You are the song that she's not sure about, but she lets it marinate in her mind, and then she likes it.
A lot of people need to be exposed to something, play with the idea without pressure, and then they're ready to buy.
(It's how I feel about the Dodge Challenger)
She was probably feeling a bit off guard at first, then warmed up to the idea of you, and now really likes it.
In your case, she was really feeling it because she moved first.
In terms of making this part of your repeatable and reliable game.
False Familiarity and Quasi Social Circle are much more passive than cold approach. But I've used it to date girls that are "in the scene". It's different than social proof, in that I'm not more attractive because others know me/I'm with cool people, or pre-selection. Instead of looking to others to make a value decision, she observes me from afar, consciously or subconsciously. And in a quasi-social circle setting (school, work, bar/night club scene), it's only a matter of time before there's social contact. This is really long game on the whole scene, imo.
Marinate - I personally think this is one of the elements of "Short Set" game. Short Set game is bouncing around the venue interacting with groups, introducing them to new people, etc, with 2/10 level of flirtation. Even if she doesn't see you the rest of that night (so no social proof or pre-selection) a good little flirt can dominate her mind and she'll want that later on.
This is a "There's that guy" type of moment. And to enhance that general effect, you don't dress well, you dress to stand out.
In terms of timeline, this is something that you can do on any given night.
That said, it's a very passive game. And ultimately, we try to be active with pick up. I do, at least. So even if chatted up a cute girls' group at 11:30 am, I would not expect her to "come to her senses" and come find me. I would do one round of meet and greets @11:30, and then I would then go back to groups that were 1) good to go logistically, OR 2) Had a girl I really wanted to talk to. In which case, if a chick in round 2 is really connecting - it may be because the idea of me marinated in her mind for a while. But that's not something I can control. What I can control is how I interact with her in the moment.
WIA