Betta Fish: Bettas tail swaying

So after I water changed her tank, I started noticing something weird she was doing..almost like her tail was swaying to one side? It's hard to describe..I got a video, and Ill put some pictures of her in the comments…she looks physically fine? But the tail thing weirded me out. She my first Betta and I wanna make sure she's okay. Most likely I'm over reacting