Introvert's compliments

At the homebrewer's meeting Paul pours some beer for another homebrewer.

The other homebrewer drinks in silence, raises an eyebrow, and leaves.

Max: What? He doesn't say anything and just walks off?

Paul: He raised an eyebrow. That's praise for us introverts.

But that guy is always soo chatty! Did you see him raise his eyebrow twice?