I trigger all the time at work because I have a very controlling boss and have real issues with people controlling me being opinionated and not listening to my points if view, do I totally understand where you coming from. With any luck he won't revisit the shop and if does hel go to another counter.Dont let him win though hopefully it was a one off. I think PTSD sufferers can trigger and will do regardless of being at work home social events etc, it's unfortunate not pleasant by any means but so true , it's part of PTSD and we have to learn to with it .