Not reacting to something

Let's say someone really irritates you.  And you really hate how irritating they are.  But you then decide, you're not going to yell at them.  You want to give them a torrent of a verbal beatdown, but instead, you're going to keep it to yourself.  (Assume this someone is your social equal.)  When you're not around that person, you yell at a wall or smack your pillow or throw crumpled paper at the ground.  You mutter and perhaps shout expletives regarding that person when you're alone, or even with your close friends -- but you just don't say these things to the person directly.

Is it denying your true feelings about something, a regrettable self-censorship, and being dishonest to yourself and/or that person?

Or is it being mature, letting things go because you have bigger fish to fry, and taking the high road?