After finding out more about PTSD I sometimes see 'symptoms' in friends. I think in the majority of cases this is projection rather than actual. But I do see common ground in the way that other people cope with stressful situations. I have probably had PTSD for most of my life, so only know my own variants (good/bad/worse/good etc.), but I believe that many people have experienced trauma and use their own coping mechanisms at some point or other. I think that being 'normal' is a fiction!