It's honestly tough to know. I've recently discovered sudden death or death in general can create PTSD symptoms in some people more prone to developing the symptoms. I dealt with someone very close to me falling very ill and eventually passing after many years of suffering, when I was nearing puberty and entering junior high school.
I was self harming, hated myself, very angry, withdrawn, and quit every sport and activity I was involved with. My mother figured I was depressed and needed to just "deal with life as it was." Looking back, I think that was my initial start to this PTSD journey of hell.
Anyway, I was drug-induced raped in 2009. I was warned by a doctor of mine to take care of it with therapy before things got bad. I, like the majority of people, waved my hand at her as to say "Sure. Okay. Right." I was sad for a bit and told people I was raped as if it was no big deal. It wasn't until a year or more later I began thinking about it more, was having weird dreams, couldn't sleep without a lamp on, began drinking a bit more, having sex all over the place to feel as though my body was mine again. I had a hysterectomy in 2010 because I worried if I were raped again, I didn't want to be pregnant because of it. These last few years things have been proven to be unbearable and worsening. I've read in multiple places that a large amount of those with PTSD don't develop symptoms and signs until well over a year after their trauma.