Is this just causal flirting?

There is this man (who is engaged), that I occasionally run into for work reasons, and from time to time I kind of pick up that he flirts with me. A few signs is that he is very attentive when we have a conversation, he compliments me a lot, stares/smiles at me when he thinks I'm not looking, and has said that he is sure that most guys won't mind me ped out on their steps, or that the reason why my guy friends always had their drinks comped at bars is because they were with me. Also, we were discussing tattoos one day, and he said he had a few, and I mentioned I had a few too, my newest being on my hipbone. He asked to see it and was heading to shut the door of his office when the phone rang. As I was leaving, he said to e-mail it to him so he can see. Is he flirting, and is it normal for happily married men to do this? Or is he just being nice? I want to know so that I can adjust my attitude around him as to not lead him on.