It started well before that. According to this article in the Washington Post, published September 2, 2008, Rupert Murdoch and Roger Ailes initiated a meeting with Obama, promising him fair coverage and listening to his grievances about perceived attacks on his wife and Jeremiah Wright.
Murdoch is quoted in the article, saying that he sought the meeting because he is "fascinated by Obama." The result of this meeting was to give Obama an unprecedented platform on the O'Reilly show on the very night of McCain's acceptance speech. Obama received Ailes' personal assurance that "there will be no embarrassing stuff" in the interview.
According to Murdoch and Ailes, NOT okay to embarrass Obama, but way okay to embarrass the hell out of Governor Palin.