HVAC isues

Have a 2018 with standard heating and A/C. In the cooler months if I have the selector in heat/vent, defrost, vents or any combo of those I go into a sweeping hard right hand curve it suddenly blows cold air out the vents momentarily. Not sure if its the right hand curve or the accelerating out of it that causes it. Dealer says its normal. In the old days ( I was a A/C SAE Certified) it was a vacuum problem but now ain't got a clue. Anyone else have this issue and if so has it been resolved?

 

I know that it's a swinging door that changes from floor/ vents/ windshield so I guess your just using just enough force going around the curve to momentarily cause that door to swing to the next setting. Nothing to worry about if that's the only time that it happens