I believe this is done often and on both sides not just one party or the other. I'm always a bit blown away when others believe that only one party stumbles and babbles and that somehow the other party miraculously does not. I'll be happy when this election is over.
That annoys me too. I was recently emailed a clip of Obama where his teleprompter screen thingee went out during a speech. He stumbled all over his words and it was uncomfortable for me to watch. I didn't see the Palin interview. But I'm sure all politicians do this- they are still human and still make mistakes just like the rest of us. I won't say whether I'm democrat or republican, but I do know these are just people who have rough days just like everyone else. Everything we see on TV or the Internet is probably edited quite a bit, just like I'd want it to be if it was me messing up in front of the world too.