Is his longer than normal gaze a way of flirting?

At lunch across the room he holds my gaze multiple times in the course of thirty minutes. No facial expressions. It’s just like hell just look up and hold my eye. I can’t help but to keep looking back at him bc I find him attractive. We’re co workers. Is he trying to communicate something. He doesn’t smile just looks?

Is his longer than normal gaze a way of flirting?
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