Some do, some don't. It's a tad annoying but not the end of the world. It's the spring on the on off button that causes it I believe. Granby had the same issue. You can pack something soft around the button to stop it, but you run the risk of it turning itself off if it's too tight. You will find you won't get it all the time either, as the spring settles periodically.
Just drop some tunes in the background and create more of a movie over the noisy bits. Jobby done
