Code found, should I worry??

[TurboWagon]

02' WRX

I had a check engine light pop up for about a day and then disappeared. I still brought it to the dealer and the code that was found was a Engine Valve that did not close all the way. They said either the sensor malfunctioned or it was a very slight occurance that tripped the sensor.

They told me the car was perfectly fine....my question is, Should I worry about it or forget it?? Is this the prelude to something serious??

[WRXin04]

Your probly fine, but if something does happen and the dealer told you its fine, itll be on their nickel, assuming ur stock,