I recently drove my car about 500 miles round trip (probably just a tad less). There was about an hour's rest time between the trip there and the trip back.
About 60 miles from home, my check engine light came on. I check my oil- normal level. My gas cap was on tightly (a problem with Saturns). My oil temp was reading at a normal level, RPMs were at a normal rate.
What's wrong with my car? :(
(In all seriousness, I am leaving to get the codes read in a couple hours- let's hope it's an easy fix!)