low oil light
 

I have a 2003 Montana, when you first start the van it has the low oil light on for about 2 minutes, after it heats up it goes off, now if i was going to start the car in 10-15 minutes it would come on because the engine is still warm. This light even comes on after i do a oil change and i know there is enough oil in the pan and everything is new. Can someone help me, would it be the oil pump.

Thanks in advance

John