Thank you to those of you who responded already.  

As some of you surmized, ArcticWesty resides up north.  Anchorage, Alaska in
fact.  I am running winter-weight 5W30 oil right now.  I have 3/4 of a case
of 20W50 for the summer.  
I just replaced both the pressure sensors, and used my Bently manual to make
sure I had the right ones. (in the right place!)
I guess my next step is to put a manual oil pressure gauge on it, and warm it
up to see what is going on.  

My "educated guess" is that I really DO have a oil pressure problem.  I could
try a sticky oil additive, but I think I would only delay the problem, make
the car more difficult to start when it is 10 below, and possibly end up with
a catastrophic failure a couple of months down the road.

I will keep in touch.  Keep those ideas coming.

John Cooper