compression issue?

[77ironhead]

I have an F350 dually, manual trans, 66,000 miles on the clock. my problem is this....just today, for the first time ever, the truck 'creeps' when I shut it off and leave it in gear (engine compression not holding it), regardless of the slope. It's 'surging' as it creeps, not a steady creep, like I would expect if the clutch was slipping. Other notes....truck empty, impeccable maintenance schedule (amsoil synthetic), engine bone stock, no power adders, etc.
Anyone have any thoughts? Is this something normal, and I have just been lucky until now? I've never had a truck creep with the exception of a loaded F150 that had a high-mileage straight-6 300 in it.