I need some advice about my gf and myspace messages that i found being nosey, you shouldve seen her reaction?

So I happend to be real nosey and at the time I felt guilty but now I do not. I was checking my girlfriends myspace why she was cooking for me and I found that she was myspacing this guy. The story goes he looked her up randomly on myspace and added her, she writes back on a personal message asking why did you add me do we know each other? He writes no I liked your picture and saw that you were a Econ Major at Dartmouth, they then proceed to talk about their work experience through various messages, until she asks him out for lunch. He declines cause he is busy with work. What does this mean? They had no common connection and I found out from being nosey? Should I be upset, by the way we were engaged.