Low oil pressure
Counting "one Mississippi, two Mississippi" the gauge had risen smoothly to it's usual spot just short of the 45psi mark and remained steady with no fluctuation for around 30 seconds of idling.
I shut it down, let it sit for ~10 seconds and restarted, needle had already snapped back to the same spot before my hand was off the ignition key.
This is with a Katech ported LS6 pump that's been on there since 2004 and has over 40K miles on it, including 11+ road course driving day events.
See how yours compares w/ a good filter.
