Interesting! Yeah, "tit for tat" doesn't make sense to me in the context of service, whether it's noodz or another form of reward. I think that ample give-and-take in a D/s dynamic can be enriching for both sides, but it's hard to think of something as "service" if you can expect something back every time you give, specifically to reward you for giving -- that sounds more like a sexual barter system. For someone who's really into service, the opportunity for service is in itself a reward. So, yeah, everything you've described makes sense to me, especially the bit about them being willing to share pix later on but wanting to make sure that the dynamic is real before going there.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.