You can also reset the CEL by disconnecting the battery and steeping on the brake to bleed any energy stored in the capacitors.
I got one pre-AP when I pulled the resonator off. Cleared it by doing the battery trick and good as new. If there is something wrong, it will log a CEL again. Now, if you think it might be something more serious than the gas cap and can deal with the blinking light before you can get to pull the code, wait so you can be sure.
There was also a way you could pull the code via the dash readout.... Deer Killer posted a thread about this.