David there's no reason to fret. It could be something simple as a lose turbo hose loose. Some guys on the
WWW.powerstroke.org are complaining about shudder and not being able to drive the truck then it goes away. I wouldn't worry until the dealer has a chance to look at it. if it happens again I would take it to the nearest dealer. Make sure that they document what is happening and if its not your servicing dealer have them send the information to them. Don't loose faith.