“It’s my understanding that Gov. Palin was offered a contract by FOX, and she decided not to renew the arrangement,” a source close to Palin told the organization. “She remains focused on broadening her message of common-sense conservatism across the country and will be expanding her voice in the national discussion.”
That sounds like the offer she "decided not to renew" was paltry, and intended not to get her to renew it. Fox President Roger Ailes has chided her in public, and has been reported to have called her "stupid" in private. In fact, one of my favorite quotes is when people lose a massive national platform and say that they're leaving to "expand their voice." I believe that Laura Schlesinger said the same thing when she departed her national radio show, and since then she...well, I don't know.
You can read more on the story here on Real Clear Politics.