The sentence used by a CBS journalist to excuse a fellow MSM outlet's is replete with hidden meanings, via Scott Whitlock in Newsbusters (thanks to Instapundit).
Fake News Forgiveness: CBS Yawns at Rolling Stone’s False Rape Story: ‘Happens So Rarely’By Scott Whitlock
The journalists at CBS This Morning on Tuesday offered breathtakingly little interest into one of the biggest fake news outrages in recent years. Talking to Rolling Stone publisher Jann Wenner about the 50th anniversary of the magazine’s founding, the show’s co-hosts managed just two questions on Rolling Stone’s false accusation of rape at the University of Virginia. Gayle King dismissed the bogus story because it “happens so rarely” at the publication.Not only does the mainstream media highlight the word "rarely," but the "it happens" construct is akin, almost, to being the passive voice. Rarely or otherwise, it is certainly a very long away from "Rolling Stone is responsible for this piece of fake news."
Gayle King dismissed the bogus story because … King sympathized, “It happens so rarely to you.”
It is as if the Rolling Stone scandal were like a natural disaster, a bit of bad luck, entirely unexpected…
In any case, as Barabbus points out, what Gayle King means is the thing that "happens so rarely" is "getting caught".