How do I confront him on this?

I am in a relationship, have been for almost 1.5 yrs. We met via yahoo personals. Recently I was looking back at our first communications and found that his profile has been active within thi past two months. I am going to confront him, but am unsure as to how. Should I ask a question that will have him answer in a lie or the truth and take it from there? Should I just tell him what I saw and ask why? How should I do this? This has not happenned to me before.