As you age, do you find yourself becoming more or less irritable?

[johan]

I'm tired of holding it in check.

I get that. But you should realize that by doing what you did i.e. going out of your way to go back to the store, in way, the guy in the store kinda won.

Let's assume the guy was just doing his job. You go back just to let him know how annoyed you are because he was doing what boss pays him to do=he just goes home thinking you're a jerk=he wins.

Now let's assume the guy was trying to be a jerk to you. You go back just to let him know how annoyed you are that he was being a jerk to you=he now has confirmation that he's achieved his goal=he wins.

If you can't let it go, definitely let it out. But try to make sure you don't let them win in the process.