Rin did not expect the situation turn out like this when she ended up being challenged by Seth.
[color=fff200]“I guess I was mistaken to think that would go unnoticed by you. Impressive.”[/color] As she was talking she was already coming up with her own plan. So far she hadn't had the chance of using her high level ninjutsu so she was ready to use them as well.

In the meantime Seth was now informing Izu that their fight would be postponed. He then proceeded to insult Rin’s ability to strategize. She was well aware of her own abilities and having them insulted caused her excitement to quickly turn to anger. Still, she knew better than to allow the anger to fuel her in combat.

[color=fff200]“Word of caution, Seth. I’m no Jonin and I’m no trainer. I’m not as good at holding back. So you’d better be able to defend yourself.”[/color] She finished with a faint smirk. [color=fff200]“I also expect no less from you.”[/color] Her expression changed to a serious one as she said that and immediately entered the stance typically used by gentle fist users. 
She knew Seth was a hothead, but she also was obviously aware of his pep talk from Akio. She didn’t necessarily expect him to charge into battle as she witnessed when pitted against Akio. By now she had a plan but she wasn’t going to implement it right away. She had only seen Seth in combat once so she was just testing the waters.

Still in her gentle fist stance she merely stood there waiting and at the same time implying she was waiting for Seth's first strike.