I guess it depends on what you mean by "going negative." I seriously doubt that she refrained from making any attacks on her opponent. Or that she had nothing to do with all those anti-Palin stories in the press up there. Maybe she refrained from going as negative as these pros wanted, but I wouldn't take her word for it, or the press's word for it, that she never went negative. This story itself contradicts that meme, although the writer doesn't seem to notice it.
http://www.politico.com/news/stories/0810/41415.html