What does it mean when a guy gives you the "triangle gaze"? A gaze that goes from eyes to lips and then back to eyes?

Is this normal and what does it signify when guys look at you like that?

My friend told me that when I wasn't looking at him my guy friend stared between my eyes, gazed down at my lips, and then looked back up at my eyes intently, (hence the name, "triangle gaze").
What does it mean when a guy gives you the "triangle gaze"? A gaze that goes from eyes to lips and then back to eyes?
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