I see some facial asymmetry. Small details intentionally incorporated into the sketch, which makes me think perhaps it's readily noticeable in person.
I'm speaking of features on our left in the sketch but they would be the right side of his face, so I'll refer to it that way.
His right ear cartilage curves in above the lobe whereas the left ear does not, it appears almost straight.
His right eye appears to have a droop in the lower lid, just below the pupil.
His right nostril appears to be straighter, a bit flattened? His left nostril has a pronounced indentation at the top.
The right side of his nose appears to blend into the cheek area while the left side of his nose has more of a pronounced edge line.
If you look at the whole nose, the left side (what we see as the right) appears more chiseled or defined.
His right nasolabial fold stays close to the nostril and corner of the mouth. His left nasolabial fold arches outward into the cheek area.
Take a piece of paper and cover one half of his face for a few seconds, then do the same with the other half.
When I do this I see a face that appears a bit more aged on his right side (on our left in the sketch). Could be an issue from birth? A mini-stroke? A mild TBI? (former military?). I've only just been reading a bit on facial nerves and I'm wondering if perhaps he has some kind of illness or injury that has mildly affected the 7th cranial (facial) nerve on his right side?
All my humble opinion.