Running properly, a car will consume a small amount of oil, some upwards of 1-2 quarts per 3000 miles, especially when the engines are new.
The oil pressure sending unit is only going to send a signal when the oil pressure drasticly drops, like to zero, and that only happens when the end of the pick up tube is not covered on oil, and it is covered when there is less than half the reccommended amount of oil in the pan. If he were to have taken a corner fast or stopped suddenly, he may have noticed a brief flash from the dummy light, but that would be it.
PAtsue did good by hearing the ticking and checking the oil. Little 4 bangers are ticky little buggers to begin with, so he has a good ear. I do not know what causes the engine to get tickier when the oil gets low, whether it is a lack of lubrication, or that the oil gets hotter and loses some of its cushyness.
It is amazing what some engines will go through and keep going. I do not think any major harm was done to the saturn.