I'm always a fan of just asking things one wishes to know, but in a relationship that is still so new (yes, I know there was a crush before and so on, but for all intents and purposes we're starting over) I can certainly see how it would be uncomfortable and perhaps a even a little inappropriate to start out with, "so, wanna' tie me up and whip my ass?" A Dom/sub relationship builds over time and with increasing levels of intimacy and trust, so should this relationship, whatever direction it takes.
During this time of reacquaintance simply tune yourself in to the subtle hints. I knew I was attracted to J-Go right away -- there was a confidence in his bearing that suggested a hint of Dom, a certain way he had of taking charge. I let him be the first to kiss me, and when he did I pushed back, tried to take control of the kiss and he didn't let me -- he wasn't overtly pushy but he put forced me back up against the wall and held me. I bowed my head to him, he immediately went for my neck with his kiss, he used his teeth a little... All signs to me, hints of that "inner Dom." As trust built between us, as the physical intimacy increased I made each small step towards my own submission to him clear. I had never given myself to someone as a complete submissive before, he had never fully stepped into the role of Dom, but little by little we found ourselves there. The steps were small but made the right way -- I don't think there ever would have been a time where we would have freaked each other out, if one of us had come to a line we wouldn't have crossed we would just have known it and been able to calmly evaluate if it was a relationship we wanted to continue or not.
Hope it works out how you're hoping.