So got home today and was excited to get things ordered and rolling for the gauges I'm planning to install. Went out to crank the car up and after a few minutes it seemed like there was a forest fire under my hood. A LOT of smoke, all coming from around the pass. side header. Looked after the engine was turned off and the air cleared and I can see oil marks on 3 spots on the headers, and a decent grime pool under it too. Now, I drove the car last around thanksgiving and there was no sign of this. All the car has done is sit for a month in mild, NC "winter" temperatures. Is this just a bad head gasket? Why did this come up so surprisingly quickly? I thought I'd be done with hg problems moving to the M113 from the M104!

Sounds to me your valve cover gasket(s) are shot. Oil drips and burning on the header is a sure sign. Those are easy to replace (both sides please if that is the cause) even if a bit time consuming to do it correctly as you need to use care and keep things clean. If you do the gasket change, think about doing the spark plugs at the same time and when the covers are off, as access to the plugs is simplified.
Keep us posted