What does it mean when a guy does this?

So at my university we work a lot with computers and i had a problem with a software and went to our unis helpdesk where there are it-specialist who help us.

This guy helped me out and i saw him today in the hallway when i walked pass him.

I saw in his eyes that he recognized me and then he smirked to himself and then walked pass me.

that smirk wasn't to greet me, but like to himself. It was a naughty and amoused grin i would say.

can anyone say me why he looked like that i really wonder what he thought when he saw me

thank you

What does it mean when a guy does this?
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