I have a very similar problem where if the truck is turned on and it was previously on a Sirius radio channel, sound will play for about 10 seconds and then stop. I have to change channels for the sound to come back otherwise it never does. It does *not* happen with FM radio, only if the truck starts on a Sirius station.
I took it to dealer and they replaced the radio inside the dash and it still does it. There is a new software update out and my truck is updating right now. Fingers crossed...