Oil light on!!('85 Coupe GT)

[Lisa Schiefer <seast@home.com>]

I was driving around yesterday afternoon apartment/ house hunting when my oil
light came on and buzzed at me for about 3 seconds then went out again. It's
never come on before so it scared the poop out of me. I was crawling along at
20 mph at the time staring at some building. I checked the oil level and it
was low no more than half a quart. I don't think it would be something to pop
on every 50K miles or so like an OX sensor- especially since my odometer
stopped at 132K over a year ago. By the time I remembered to check the oil
pressure gauge, about a minute later, it read 5 bar like normal.
	So, what could make it come on _and buzz_ under such tame conditions and with
plenty of oil? I've made the light flash before in a couple 270 degree off
ramps; but not buzz. Been running errands today with no problems. BTW; Using
Castrol 20-50, last changed 3 months ago, occasionally topped off, but doesn't
really burn oil. "Swepco 502 oil improver" added at every other oil change to
quiet lifters: IT WORKS. 
	Any ideas besides a ghost in the machine? 
thanks,
Shane East