Different O-Ring in the picture. The M Kline valve has two O-Rings instead of one. The one in question is factory installed and I have never heard of any recommendation to lube it.
The owner read the manual and only saw the one O-Ring in the picture, so he never checked for the second O-ring.
I just assumed the factory did things right. I didn't feel like potentially damaging the Kline valve by unscrewing it.
Any accident is avoidable.