I´d like to point out that everyone can have triggers without being aware of them. Even people with no abusive background whatsoever. Or it might be something no one ever did to you before. Even if it is done by your loved one, it can be a trigger.
For a gay friend of mine, it was being slapped.
For me, it was getting spit in the face.
Sometimes you hate the triggering action so much you avoid it at all costs.
Sometimes you start to include it into very intense play sessions.
It´s your feelings and your decision.

I used to think only things which had happened to a person before, especially in an unwilling context, could turn out as triggers. It is not so.
This is for the Doms out there who happen to stumble over a trigger and feel bad about it... it´s not your fault.