I checked around today on this. Is this in your 92? If so and I am reading into this right it sounds like the flasher circuit in the integrated control unit is lighting up the oil pressure indicator light indefinitely during operation given the reading from the pressure switch. If that is the case, I wouldn't be so light-hearted about it as some. The oil pressure indicator light is never to be ignored.
The indicator should light when the ignition switch is ON (number 2 position), and go out after the engine starts. If it starts flashing, it indicates that the oil pressure dropped very low for a moment, then recovered. If the indicator stays on with the engine running either stand-alone or just after flashing- it shows that the engine has lost oil pressure and serious engine damage is very well possible. In either case, you should take immediate action. Personally, my key would have been out of the ignition in about two seconds and I would have called a flat bed having already learned my oil light lesson. :wink:
My take here given the info I have is to assume the worst and hope for the best. Best case, as the oil drained out it likely cavitated and sucked in air firing the light and you caught it and quickly shut it down around idle speeds just as you were pulling in. Much will likely depend on just how quickly you caught it as it only takes about 10 seconds to fully empty the pan with the bolt gone. It it went much beyond that in your estimation given the lingering pool in your driveway or you were ratting on it at the time before pulling in ... I don't know...
Only good diagnosis will reveal. A fuse, wiring, or a sudden faulty switch is probably unlikely given the circumstances. The fact that with a fill it runs is a good sign but honestly tells little. I know that the tendency seems to be to fill-up and hope for the best and think it is either good or not... but there are a lot of grey areas in between those two points.
Given the circumstances, if it were me at the bare minimum I would recommend having the engine oil pressure checked manually to ensure it is to spec before it is driven further. A competent technician may also further follow-up with a comp/leak down and cutting the filter open depending on the out-come there.