I called a couple GMC dealers around me, including Roper GMC in Joplin where I bought it, and none of them ever heard or seen this issue...Course they all say bring it in and they'll check it out..I said, HOW?..now that it's working fine you won't be able to find the problem...They said they would re-flash the system in case there is a bug or two.
I haven't had the problem since I last posted here about it, or since my last XM update.....In all, it's happened 3 times.