Yes... a trigger for someone with PTSD is something that reminds them of their trauma and so can send them right back into the experience. With complex trauma strong emotions can be triggered by relatively innocuous input, because the person is sent back into the emotions they had in the past, often as a child. I am very easily emotionally triggered by what I perceive to be snide and/or b****y behaviour, and cliques, and there's a lot that I perceive that way around here.