2015 VW Jetta Oil Smoke On Start-up

My wife has a 2015 Jetta with the 2.0 NA engine. It has about 75K miles. She works from home and doesn't drive it much. After the car sits for a few days, there is oil smoke that comes out of the exhaust at start-up. The smoke does not continue during driving and does not return on start-up if the vehicle has been driven recently. I assume this means there is a very small oil leak somewhere. What I am hoping someone could answer is: what is leaking and how urgent is it to repair said part?