Is he attracted to me?

I have been very unsettled all weekend long! This guy I have known for a few years really got to me. We were casually talking and I happend to look down. When I looked back up at him, he was staring at me and we locked gazes for a few seconds. His pupils were so dilated that I felt like I was looking right into his soul. I finally looked away as it caused some strange feelings in me. We don't see each other very often, and he's an attractive guy, but I've never felt like that around him before. It really bugs me as he has a girlfriend for 5 years now, and I'm happily married going on 11 years and he knows that. Did I read him right or did I get the wrong impression from him?