Enjine oil pressure gauge

I have a MB s class model s320.IS it normal to have the temperature  oil pressure decrease when the car is at constant stop at 0km especially waiting at traffic light?.BUt when the car goes the oil pressure rise immediately.

Totally normal.........Oil Pressure at idle (normal operating temp. of 80'C) should be at or above 1.3 bar and then rise quickly to 3 bar (max. gauge reading) around 1500 rpm.