I doubt there is anyone who has experienced extended combat who is not affected to some degree with stress, but some deal with it better than others.
Gomez brings up a good point and you do too, Grm. From other vets who I have talked to, if the people at the Veteran's Administration ask a combat vet if they ever dream about what they experienced during their tour, then they qualify for PTSD. I think we all had but many of us can handle it. Why many of us never talked about it for years after we came home.
My personal thinking on it, and I could be completely wrong here, is that it comes down to today society. As a boy I was raised to believe that males do not show their feelings openly, let alone share them. The attitude was that a man walled those feelings off and didn't talk about them, chose not to feel them, put it behind you. You learned to keep it under.
I know my father
never talked about combat, and I've certainly never shared what I went through with him or any others who weren't there. Not my wife, not anyone.
Now it's different, these people are encourage to "share" their feelings, get them out in the open. For many I think this just keeps those feelings fresh and painful, like picking at a scab.