Daylight running lights stopped

2003 Chevy Impala - I usually dont turn on the headlights. I just drive with the daytime light system turning the lights on when I start the car. I drove to the store last evening in a fairly heavy downpour. When I stopped at the store I heard a popping sound like a litebulb burning out. I think the sound came from somewhere under the car. I turned off the car and did my shopping. When I came out and started the car I noticed the daytime running light syste m didn't turn on the headlights. I pulled the headlight switch and the lites still didn't come on. I tried the high beam switch and they wouldnt stay on unless I heald the lever. No clicking. All the dashboard and door lights were working fine. I tried the map lights on the mirror and they didn't work. The mirror auto dimmer didn't work either. I drove toward home still raining. All of a sudden the mirror lites came on and the headlights were on. I am confused. Did I run over a puddle and water got into something? I dont know. The car is in excellant conditon with about 38,500 miles on it. Any ideas about what caused this to happen would be greatly appreciated. Dealers cost around $110 an hour in my area.