Two things,
First, Muzikman is absolutely correct concering the function of the Gen2 4x4 system.

Second, Paul, my truck does that too. I come out from work and start the truck and get the SLIP & VDC OFF lights. The next morning I'll start it up and the VDC OFF light is still on but goes off a few minutes later. This has been reported on this forum before, I think everyone is just learning to live with it now.