She does not look easily impressed. That is the part that lingers after the first glance.

A compliment may land, but it does not rearrange her face. She has heard enough pretty lines to know when a man is filling air and when he is actually paying attention. So he adjusts. He sharpens the joke. He chooses the next sentence more carefully. He waits longer for the reply than he planned to.

The first look did not seem to buy him anything. That is why the second one lasts.