For what it’s worth, I think “secret shopper” was being a jerk, trying to control your behavior through manipulation bordering on intimidation. I know it part of the job, but all of my friends who worked retail used to say “Just wait until my last day, I’m going to tell these jerks exactly what I think”, and of course none of us ever did, but the planets aligned for you, and I don’t blame you for taking advantage of the opportunity in this one case. Particularly in that the way Spot has been treating people lately isn’t setting the best example. I believe 100% in the Golden Rule, even for people who don’t necessarily deserve it, but that guy major league wasn’t using it, was being a manipulating jerk and I wouldn’t have apologized to him “on demand”, either, although if he hadn’t demanded it, I would have apologized to him and everyone else in line for the delay.
Congrats and good luck with your masters! Don’t look back and enjoy Life after Target!