Moaning

I moan A LOT, lots of little things annoy me and I am the type of person who just cant keep my mouth shut.I wonder if anyone else has the same problem? the things that annoy me most in order of annoyance, bad parents, bad driving,bad parking,children in adult areas of the gym, shop staff who give rude/ indifferent service, rudeness and bad manners in general.
I came to the realization recently, that I am a grumpy old woman, a female Victor Meldrew and I don't know when it happened.
My husband is long suffering and puts up with it most of the time, but he has on occasion been heard to mutter under his breath,for me to give it a rest.
I don't understand why moaning is a problem it is an instant complaint of whatever is annoying me at that particular moment in time,its over and forgotten about as soon as it's off my chest, and it is a release for my frustration and nothing is bottled up to explode later on.
Because of my moaning people sometimes seem to get the wrong impression of me and think that I am either miserable or angry all the time, I am neither. I am quite contented with my lot and most of the time I'm reasonably happy.
I know it annoys people but I don't know how to stop as it is an unconscious reflex and I have opened my mouth before my brain is in gear. I wish I knew how to stop but if I bottled it all up, I might just end up punching someone instead,