PTSD can arise from events you wouldn't always expect them to. I was traumatized simply by having repeated, severe illnesses over the course of many years, which was the cause of my OCD (germaphobia). I was told this by my pdoc 2 weeks ago. I don't think it's fair to automatically assume a person does not have PTSD/was not traumatized by an event just because it seems unlikely to you for said event to cause it. At this same appointment, my pdoc told me that what may traumatize one person will not always traumatize another. It's very individualistic and dependent on numerous factors.

My actual PTSD that you see listed in my signature was caused by something completely different, just to clarify. BUT it is possible that someone could get PTSD from something as unlikely as repeated illnesses. Whatever the event, it really does depend on the individual. So yes, I do see 9/11 as being a very possible cause for PTSD, despite not having actually been there.