As I mentioned my S has only been in existence in the cold weather so far; Made in December, and in the Colorado mountains it hasn't even warmed up yet, it snowed last week. It's not heat. As far as 2017s being fine: Yes I've had a 2013 and 2015 loaner and both had clear screens with no yellowing. Looking at the anti reflective coating, screen color temperature and differing quality, those screens were slightly lower contrast and had a cooler color temperature backlight, and were obviously from a different supplier. It seems that the changeover happened sometime in late 2017 or early 2018 to the new style of screen, which yellows.