Update:
After a day or so of driving around the oil pressure light started acting up again at idle. But as soon as you touch the accelerator the light goes away.
Searching this issue kept poping up with oil pump wear or bearing wear. It was strange due to the fact that the mechanic gave a clean bill of health on the engine.
So long story short after lots of testing we found that a stupid o ring on the crank case ventilation line was worn out and wasnt providing a good seal on the tappet cover.
Bmw does not stock these anymore so i wrapped some insulation tape around the seal as a temp fix...
Drove the car for 2 months now daily and no pressure light