For some reason this new recruit I have started with 50/60 Hitpoints. He has the Tough trait, but I never noticed this behavior before. So I even started a couple new games and bought dozens of new recruits until I get one with that trait. When I got one he had full hitpoints, though, so perhaps it happens when a certain mix of Background or other existing Traits appear together. I dunno
This is not game breaking as the recruit will probably heal before a battle, but at the cost of the company healing items… so I doubt this desirable.