When did Sarah Palin become politically-correct?

To coin a phrase, it's "selective political correctness". She only calls out the democrats, not republicans (unless she deems them RINOS) never conservatives. She called out Ralm, but not Rush because for Rush, it was satire. Funny, I didn't think it sounded like satire, but let's just say for the sake of argument it is. Then what about Letterman, that really was satire. He's a late night comedian, not a pundit. If anybody should be allowed a p for satire, it's him. Has Palin publicly said letterman was off the hook?