What did Zach notice about Willie's hair in Chapter 7?

Zach noticed that Willie's hair was lighter.

Willie looked blankly back at him, and pushed his fingers through it. His scalp didn't itch anymore. It tingled.

"Wot's wrong wiv it?"

"Nothing. It's just a different color, that's all. I didn't realize you were sofair."

It was true. The lank look had disappeared and it did look lighter.