Had my oil changed at a reputable place. Got a couple miles down the road and oil can light came on but only while stopped. The place had closed so I couldn't go back. Checked dipstick and it's got plenty of oil. Ran thru the digital gauge and watching the oil pressure it looks like it's dipping down to 4/3/2 psi while stopped in drive. As soon as I rev or drive the psi goes up and light goes off. I don't have a baseline since I never watched how low the psi got while stopped. Anybody have any ideas?