Oil Pressure light on?

Folks,

My son, in another city, is driving my 1996 Maxima with about 120,000 miles. After hitting the breaks hard a few days ago, the oil pressure light came on. He called and checked the dip stick (OK) heard no unusual noises and went home. Next day, he brought it to a local mechanic, not a dealer, who could not find the problem, says the car is mechanically OK. The light remains on.

What do you suggest? Should he just ignore the light? If not, how urgently should he act? Thoughts on what it could be and approximate costs to repair?

Thanks in advance

does he have a "check engine" light on in addition to the oil light?

No, the check engine light did not come on.

you may have to take it to the dealer. im lucky enough to be running fine on a 95 max with 140000, still drives like new so it shouldn't be anything with the engine.