Low oil pressure warning at idle(700 RPM) when warm

[Walter Sobchak]

I get the low oil pressure beep when the engine is warm, and oil temp is 80 ish, if I go to the oil pressure it's showed it at 3 PSI, however as soon as I apply revs even to only 800 RPM the pressure is fine, I've just had the oil pressure sensor replaced as it was dripping, the car has just had a service and I was told the engine is very healthy, is this anything to worry about or fairly common?, as I say it's only when the car is warm and at complete idle it doesn't always do it either seems to more if on an incline, is this just a case of it being a big engine to get the oil around and at idle there isn't alot of pressure?, or is the new switch giving false readings maybe?.
Maybe the idle is slightly too low as it's at 700RPM but sometimes goes down to 600RPM.

Edited by Walter Sobchak on Sunday 17th January 00:42