Thank you for the answer and insights. I should admit that when we saw each other last month at a conference, we had a few too many drinks. As we walked out of the conference, he admitted to me that he was 'attracted to me, more than he should be.' He was also rubbing my hand and asked if he could kiss me, and I declined. I think we just decided to ignore this incident, but with us working a bit more often for the foreseeable future, I guess I am a bit more aware of what he says, and want to ensure an interest is not there.
Thank you so much. Sorry, one more follow up question/request for advice. I am the main point of contact between him and my company. He essentially endorsed our company to his colleagues which will give us business through next fall, business that is valuable because we are a small company. He did tell me that he respects my work and that I do a really good job, which he says adds to the attraction (said during that same encounter last month). Am I ok not telling my boss about this? I prefer not to, I like to think I'm competent and can handle this. But do you think there could be repurcussions from his end with me stopping my flirty behavior (I have to take responsibility for this as well, I was weak and this attraction thing caught me off guard).