Why was Via so upset that Auggie had cut off his Padawan braid?

From the text, we can infer that since Via was already upset... Auggie's cutting off his braid made it worse. He hadn't even discussed it with her.

When August cut his braid off that night, without an explanation, without telling me beforehand (which was surprising)—or even calling Christopher—I was just so upset I can't even explain why.