At poodagr; I work there as an instructor, so it's not all that special they walk up to me. I think

And whenever they're on the treadmill / escalator machine or whatever, I can just stand next to it and start a convo. Though I guess I can get away with that being an instructor there! I might be weird when you're just some guy training there aswell. Though I guess getting on the machine next to it is pretty good.
All of these cardio machines are actually really boring (you're running for 15 minutes without moving an inch!!). So just start chatting with them. Most of the time they will be happy as the time will just fly away when chatting.
Anyway, I had this girl coming up to me a couple weeks ago for a workout and helped her out. We were getting along pretty good and all. Gave her some kino (although it was more work-related then to seduce them) by feeling if she had a straight back or was squeezing her shoulderblades together etc. Like I said, not much seduction related.
So, she usually comes in on friday's (that's when I work there), but she wasn't there last friday. I guess that can happen. I went to do my own workout the day after (saturday), and she came into the gym when I was just about done with my workout. So I waved and said Hi. She came up to me and I asked her where she was yesterday (meaning friday). She told me she had some trouble with the traffics and didn't got home till 2030 hours, and couldn't come. We had a little convo and I said something like 'Well at least I still saw you this week', smiled and she initiated a high five (kino?).
I'm not sure if that's an IOI (or multiple, as she came over to me when I said Hi) or she's just being nice and friendly. What do you guys say?
Anyway, to come back at my original question. I should just go and chat about something deep, and break up the convo somewhere in the middle. Then ask them to continue the convo later on, but suggest somewhere outside the gym?
What if they respond with something like 'next week' or anything suggesting the next time they're in the gym? Can I take that as a way to say they're not interested?
I'm pretty new to this whole community, hence all the questions. Also pretty insecure about myself and tend to onverthink alot. Though I have to say I'm getting more and more secure the longer I work there.
Cheers,
NAB