A few years ago I was the victim of an aggravated burglary, I wasn't badly hurt but it was absolutely terrifying. I did have some PTSD symptoms and some treatment afterwards and feel I'm mostly ok now, except for one thing. I can't answer my door if I'm in on my own and not expecting anyone, to the extent where I literally hide 
I feel utterly pathetic but can't seem to help it, I instinctively duck away from the window and scutttle off to a room where I can't be seen, then I stand there frozen until they've gone away.
I know it's not so unusual (on MN at least!) to not answer to unexpected callers but I feel like a complete weirdo because I react so strongly, it's not normal is it? It feels OTT to say I'm still suffering from PTSD because it's only this situation that provokes that response now and it doesn't happen that often but I just want to stop freaking out because the bloody doorbell rings!