2019 A6 3.0 , 26,4XX miles.

After a cold start ie sitting overnight, I get a warning to stop engine and check coolant.
After running for a few minutes, If I shut off and restart the light disappears and the car runs fine.
Temp gauge shows normal under all conditions.
Thsi started shortly after an oil change/service and I dont feel like spending a half day at the dealer.
any Ideas?

 

Stopped by the dealer, after finding the filler they topped it I think they underfilled at the oil change 2600 miles ago.

If the warning shows up again, I guess Ive got a leak