Oil warning light on at strange times (CGT)

[only5kgt@uswest.net]

As per subject...
Three tims in the last couple of days, I have suffered that
heart-attack reflex which occurs when the oil light blinks
on in a beloved vehicle. Patient is the Coupe GT '85. I have
been rolling along anywhere from 30 to 50 mph in 3rd, I'll
hear a beeping sound never heard before, I look down, the
oil light's on! Eeeek! But after two seconds or so, it goes
off. Now, before the obvious answers come up:
There is plenty of Valvoline 20w50 Racing in the sump,
and...
the factory gauge mounted in the aux panel displays nary a
quiver, stays at 5 bar like always.

I am thinking some fault in the wiring or sender? Or is
there a big chunk o' ugliness finding its way into the oil
pickup? The gauge's constancy calls this into doubt, I hope.
I drive this car *hard* and I was looking forward to doing
so over the nice 4-day weekend coming up (both SoCal and
northern AZ are looking good right now)...don't wanna blow
the I-5 up on I-10- thoughts, anyone?

The light works in sync with the gauge usually (light on and
tappet tick on startup, momentarily, followed by shutoff of
the light and silence from the top end as the gauge swings
around to 5 bar)...

Somewhat unnerved in Tucson,
Rob