Palin campaigned for McCain in 2008, helping him stay in office. She has never said anything to denigrate him, despite nasty anonymous attacks on her from his campaign people. But she cut bait in Iowa:

We got blamed! They called us un-American and terrorists and suicide bombers and…hobbits…couldn’t understand that one.

She was referring to McCain labeling Tea Party Patriots as hobbits.

Sen. John McCain on Wednesday took on conservatives reluctant to raise the national debt ceiling, calling them “tea party hobbits” and saying that if they reject the House Republican plan, they will help reelect President Obama.

Note the “couldn’t understand that one”.  She knows McCain said “Hobbits” and she is calling him on it.