Hello folks... I am retired some 5 years now.I worked in a secure unit for most of my career. I tend to get flashbacks and vivid dreams from long ago. not necessarily from my last job. Also bizarre dreams totally unrelated.Brevity... is it just the brain "cooling down".. or what?
I can only speak as someone who dreams almost every night, im 22 but i have dreamt of almost every single situation you can think of. I dreamt of my old house i used to live in, it was covered in cobwebs... perhaps a relic of the past? Dreams can say a lot. Also, ive found out that what we think about a lot when we're conscious, tends to be the subject of dreams. As long what you dream is not bad, or harmful, or you know nightmarish types, id say its a nice gift to have. But as you put "PTSD" in the title, it might be painful aspects of your past career coming back, stuff you could not deal with at the time... the brain needs to sort this out, to make sense of it, so it does so by dreaming about it, trying to intepret it in a way it can do so, so you stop thinking about it and stressing yourself out. I hope this might help in even a small way... good luck
Quite correct. The kicker is when a dream , or a series comes in , say 3 years later. The brain is the biggest hard drive, but tell it that when you are reliving ....
Are you on any medication??? I take medication for both depression and anxiety. I worked in Mental Health but my dreams are not connected to this!! They are extremely vivid and wake me up I could be falling, spinning or just retracing footsteps. It's not nice as I feel afraid to go to sleep or get extremely drunk so I just pass out so that I don't dream hopefully. But unfortunately it is a side effect of the meds so what do you do???? 
stewart..I do not know about " cooling down '... however, while working the brain seemed to be busy. Then when not so busy certain what was mudane now becomes a trigger. Some help can bring you to a lesser painful mesa, however it takes time.