You'll notice that in the previous page in the third panel, Thumbs-Up Man has no fedora on, and in this page, he does on the first panel, but then it is missing by the second panel!
Zach's hairline has retreated in the first panel, and his eyebrows have begun to get bushy. This is a premonition to him turning into Hcaz, since it's triggered by him becoming angry.
-- Tsitra563