Truck Forums - None of my gages worked

My '03 Silverado........ Went out this morning to go to work, and started it up early to let it warm up (Approx. 20 Degrees outside). Just reached inside and all one motion, started it up, rather than turning the ignition to the on position, let it run thru the cycle of checking all systems etc. About half way to work, i looked down and the speedo,tach, temp and oil pressure gages were not working. Not sure if the odometer was working or not as i did not pay attention to it. Called the dealer and said it could be a couple things but w/o doing a diagnostic ($90.00), they could not be sure what was happening. So, i got to work, turned off the truck and just for Gits and shiggles, i started it back up, by going thru the turn key to on position, let it run its course, then turned ignition to start it. Started right up, and all gages were working properly. I just got out of work, 9 hrs later, did the same routine, turn to on position, then start engine and its working fine still. Any ideas why this morning, it acted like it did? First time its done that ever since i owned the truck. I have 95,000 miles on it. Thanx for any ideas in advance, Jim