yes having "flashbacks" is normal with PTSD. after huricane sandy I had many flashbacks where for a moment I felt it was hurricane sandy coming with every storm or light rain. anything that reminded me of that time in my life I felt for a moment that it was happening all over again. one day my wife found me staring out the window on a sunny day, she asked me whats wrong and I said just trying to blink away the huricane. she went outside and waved at me from the window. I realized seeing a neighbor spraying his sprinklers that morning was causing me to "flash back" in the form of visual hallucinations.

my suggestion is if you have a treatment provider contact them. they may have some ideas for combatting your flashbacks or maknig changes medically like some great anxiety meds can slow anxiety responses like anxiety induced flashbacks. works for me anyway.