Just now staring at this issue. I have now noticed while installing new carpets that my lower AC vents are both canted over to the right in very same amount. They are not pointing straight back.I did move and repaint the dash panel.
I removed both vents to see if I had installed them incorrectly in another possible screw hole of which non exist.
Factory assembly anomaly or are they supposed to be this way? If yours are positioned straight, could you shoot me a pic so I can swing them straight, drilling the appropriate new screw hole? So as not to mount them too far forward or back.