Volvo: Oil Pressure light flickering, electrical contacts, oil pressure

Question
I have a 1990 240 DL sedan that I've been driving for about 9 years.  I've had to have the alternator replaced 3 times in the last six years.  The most recent time was just yesterday.  Now the oil pressure warning light is flickering on and off.  It seems to be unrelated to my speed, braking, etc., but it's not solidly on either.  I got the oil checked/changed immediately (I was due anyway), but the light is still flickering.  Any idea what the problem could be?  Could it be related to the alternator repairs?
Also, are there any other typical things you might suggest I get checked out that are common in the car at this age?

Answer
The oil pressure pickup sensor is actually right behind the alternator screwed into the lower engine block.  There are several electrical contacts that could have easily come undone when they replaced the alternator, causing a random short.  I would check to make sure all the wires are connected to the sensor.