Berry -- a very vocal athlete in the fight for social justice in America -- was so pissed when the anthem played at her podium ceremony ... she did everything she could to express her dismay with the song.
The 32-year-old turned away from the flag, held up a T-shirt that read "Activist Athlete" ... and said afterward she thought officials were setting her up just to see how she'd react.
Jenner -- who's now gunning to be California's next governor -- says the whole scene was B.