221425
Went, you have to take her entire personality into consideration!
In that screenshot she's trying to act intimidating because that's what she thinks is expected of her as a fire gym leader. Heck, she even drops the façade when you beat her in the games, because you make her feel more self-confident in her own personality.
I wouldn't expect her to act all over-the-top and threatening while she's just hanging out with her favourite 'mon during her free time. :P