Never from what we were told. But the idea here is that she is like this all along, but uses her powers to hide it in the face of everyone. But as we are immune she cannot pretend, so she doesn't even bother.
Also, I can understand the hate for her newer versions.
While at first both in comics and in the old cartoon she was as good a character as everyone makes her be, the voice of reason and emotional support of the team while still having great power, to the point they had to make her lack stamina not to steamroll most enemies. Thus why the whole Dark Phoenix thing was such a change for her...
But after that people seem to have forgotten her old character, only that everyone loved her and how much it sucked when she became evil, and she went from the one who keeps everyone sane to the canon mary sue.
Just look at her Evolution version.
She tries to be like the old one, holding back the others from making most stupid things and follow the rules... but instead of sensible and calm she ends up being forceful and preachy.
Her boyfriend is an asshole and that is made clear from his first appearance, and it is hard to believe she is not aware, but she still does nothing and they only break up in later seasons because of his dislike for mutants.
Also hard to believe she did not know Scott liked her there, there is one episode Kitty and Kurt break Scott's car to throw a party and she mentions it is a cliche, yet she clearly did not just tell him she was not interested.
