Guys, Why did a guy look at my face four or more times?

I know it's probably been asked a million times, but I saw a guy I had a crush on from college. I haven't seen him in a while and he looked at me at least four or more times. Maybe he was trying to remember me and that's all, but what else can it indicate? He looked slightly nervous also.

Guys, Why did a guy look at my face four or more times?
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