The problem is that people like Palin work everyone up telling the country that Obama pals around with terrorists, and that he's intentionally trying to erode the country, and THEN they put targets on him. They do this for the real Americans; the ones that know that no one should stand between them and their guns.
Of course she didn't mean to go kill politicians, and of course people use those terms every day. But put it into perspective. If you stoke a fire and stoke a fire, eventually throwing in a single firecracker can blow someone's finger off.