An incorrectly replaced gas cap is one of the most common reasons for triggering the Check Engine circuit. Did you check your gas cap and see if it was on correctly or not?

If it was on correctly and tight, then I would discount the dealer's advice and get that Crossfire in to them ASAP. If it (the gas cap) was loose, then indeed follow the dealer's advice. After a few starts with the gas system pressurized, then it will clear up.

This is one of those times when you wish there was a Engine Code Display mode, so that we could pinpoint just such a situation.