Oil pressure light will intermittently flicker on when engine is cold.
Flickering stops within a minute or so, and sometimes does not happen at
all.  Have never seen this before.  Have about 50K miles on Boston
Engine long block I installed in 2003.  A couple of months ago,
instrument cluster (new around 1999 and new style which requires
grounding of circuit for second oil pressure sensor) had to be removed
to replace master brake cylinder. No problems right after that.  Also,
no significant oil leaks and crankcase oil level between the two marks
on the dipstick.  Engine sounds and performance are normal.

Have I missed anything in troubleshooting?  Do I need a new oil pressure
sensor?

Thank you,

John