She says she isn't...but...
It's like she's trying to create that 'sibling distance' but (1) - he's already been 'formatted' for her ...
(2) - she knows she's got a good thing going and she doesn't want to give it up just yet.
I bet if he didn't have the ability to pilot an IS, she wouldn't have really cared since she was away from him for long periods of time, but now they see each other pretty much every day...