Case of mistaken ual tension?

I'm intrigued. Can ual tension in the office be mistaken? Initially I wasn't at all interested, being married, but raised eyebrows with a smile, managing to sit so close to me we were touching (his move not mine), rather extended direct eye contact when discussing things, intellectually challenging each other and he replied to my joking emails for a postcard on his holiday. He's much younger but given his pretty high intellect we seem to be on the same level. Am I uming something is going on here needlessly?...(and no sermons on retaining a happy marriage I've heard them all)