Hello tholr! I use to live in the southeastern part of the USA where you are now. There are frequent electrical atomspheric conditions in that area. Perhaps there was a very unstable envirnoment the night you went to sleep. Maybe you just hit a bump at the wrong time your vehicle computer was making a critical decision or it could be a freak instance that the puter just hung up in that memory area for a split second(ie.. much like the one does on your desk right now).
As stated above, there are several things that will cause the onboard puter to send a warning code to the lights on your dash. My trac light and ABS light came on about 3 months after I had my truck. The two came on when I started the truck after it had been sitting for a week. They were not on when I stopped the engine after driving the previous weekend. While sitting for the week, it rained often here in So Calif. and there had been a couple of brief thunderstorms. Anyways, I drove the vehicle for the day about (150 miles) and the dashlights never went out. Upon returning home, I disconnected the battery for one night and then reconnected it the next morning. The dashlights were gone and I reset the auto windows/sunroof features. The problem has never returned to this day.
You can always disconnect the negative side of your SUV battery for 3-4 hours to see if it resets the system now that you have already went to the dealership. Perhaps your puter just glitched once when failing to read the knock sensor and sent the code by default. If the sensor is really bad.....trust me, it would send the code again. Just a thought from my experience.