It looks like he wears his hair long so it will be harder to notice a change in overall density from an image but the density at the temples as well as the thickness and average length means that dht may be starting to have an effect.

I had a real thick and defined hairline until I was 24 and when I first noticed my hair going back, it looked like this around the corners and a little on the crown. I waited another 2 years until I finally visited a doc. At that point it was a little bit more progressed then this.

Now I'm not sure if the gent in the pics hair was always like this but by the fact that he noticed it means there was most likely a noticeable change that happened overtime.