Part of the adorable nature of Doms, to me anyway, is that they push what's comfortable just a ticky. I like a man that is not afraid to question the specifics of what I say or one that probes for more information. Keep me on my toes, please! Verbal sparring is a huge turn on.
As with anyone, however, there are things I do not share until certain levels of trust are reached and when a man, or woman for that matter, hits those levels I do point out that what they're asking about it a topic I need more time with them to feel comfortable before I'll discuss. I make sure that the tone and verbiage I use when telling them this is distinctly different than the banter we've been sharing in a friendly and coy way.
So, I'm curious before I give this prospective Dom the thumbs up or down - was it clear that you were putting the brakes on or could it have been mistaken for sterotypical D/s flirting? Doms want to come off as Domly, after all, and this could be what he assumed you expected. First date and all.