The computer will reset itself after driving your car 3 different times if the error is gone. My guess is that nothing was wrong with your EGR valve but instead your EGR port is clogged.
Look at the sticky on the EGR and Intake Manifold cleaning
DIY: EGR and Intake Manifold Cleaning
This will show you how to get to the EGR port to clean it yourself. If yours is like mine it will be nearly clogged shut in the tube and the backside of the intake manifold. I cleaned mine best I could and 3 trips later the light was off. No need to replace the valve.