All the side glass has distortion. It’s not like the rear glass where it’s really obvious, but the easiest way to see is if you look out at a tall building while stopped through the side windows and move your head around while looking at said building, you’ll see that distortion. It gives my wife a bit of a headache.
Now, since my new S is in the shop for the 400th time, she’s enjoying our 2017 Model S 75D loaner because the single-pane glass has no distortion at all on any of it!
As for the windshield, if you’re particularly sensitive you may notice some distortion on the passenger side when sitting in the driver’s seat, and vice versa when sitting in the passenger seat and looking across at the driver’s side windshield. It manifests as a slight “rippling wave” effect about 80% of the way down the windshield, running laterally. I tend to notice it only when going round a corner and looking across the car. Most won’t notice it.
A few of us (myself included) had localized distortion in a smaller, specific area that was out of spec, and thus had the windshield replaced.