When Reading the following....
Bear in mind I'm the sort of chap that when faced with a "Check Engine" light and I can't find the fault, I usually remove the dash and take the bulb out of the "Check Engine" socket!
Anyway, I would say if everything is working fine, then it's probably just the LED itself that has "gone phut" and I wouldn't worry about it. Just keep an eye on the unti for a couple of weeks and if you're still worried, get into the habit of unplugging, not just switching off, the thing if / when you leave the room for any length of time.