That sounds familiar
Same thing happened to my 99, it was the center cab light seal. the seal had a small cut in it and when you would stop going down hill the water would run tord the front of the cab and into the overhead console. If the truck is still under warranty take it to the dealer because most likely the trip computer will need to be replaced like mine. My dealer fixed the cab light seal and a couple of weeks later the trip computer died and they had to replace it.
Big D