Am I going to be an odd guy?

After dining with some of my senior high school classmates, I found myself really worse to participate in their talking even if I miss them so much. Does it reflect that I'm going to get my life separated from theirs? The main issue is that I can't find any common topic for talking except those happened during the past senior school time or the other classmates of ours. Although I try to avoid judging this situation which is most agreed to be sensible, I still feel confused why I become so incompatible. If it's getting hard to find something fresh for talking, it makes the gathering duller than just staying home, doesn't it?