Im not a psychologist, but I think that you are reacting to something that really happened to you. I would guess that a normal reaction from an untraumatized person would be to wince and look away from a graphic scene in a movie. It sounds like what you are describing is a dissociation from the graphic scene.

If it bothers you, which it seems like it does, otherwise you wouldn't be talking about it, you should look at getting some relief from these flashbacks.

Sorry you are experiencing this. It sucks having your day interrupted by unpleasant experiences all the time. Hope you find relief!