For your info, I found the source of the low oil pressure. I had changed from 10W30 to 10W40, and saw absolutely no difference in pressure. I then changed to a new oil filter. I didn't think changing to a new filter would make a difference since the current filter was only 3 weeks old.

The new filter solved the problem. Apparently, the 3-week old filter must have been defective, maybe a overly strong check valve.. Nice to have a $8 fix to the problem........