I think puberty makes some girls sassier. I got more willing to challenge authority then, too. Back when I was a middle schooler--in the Dark Ages!--boys were allowed to wear shorts to school, but girls were not because it would be "a distraction." <eyeroll> Given that the school was not air conditioned, the heat was a distraction to the girls!
I talked to a favorite teacher about it. He said "You're right. It's a sexist policy. What are you going to do about it?" I wrote a scathing (but polite) editorial about the policy, and I got it changed. Woohoo!
It was scary for me though. The boys were all mad at me at first because they were afraid the administration would change the policy to stop allowing boys to wear shorts! Happily, they chose the smarter route.
Shorts (grazing the knee) for all!
And like you, I prefer my sassy self over my sheeple period.