I dont have one but know about them. 6 vibrations means its powering off. 1 means ON setting High 2 means ON setting Low
I think you are suppose to hold the button in for a few seconds to power off. Then you feel 6 vibrations to confirm it's turning off. But no I haven't heard of any issues with it turning off by itself or on any other setting.
doesn't it come with an owners manual ? if you bought it new,it should have an owners manual to tell you how to decode the various vibrations it makes.