Odd question in a way as not many users visit the forum but I don’t have the problem.
You mean when you pull it out of your pocket you have to power it on, or whilst in your pocket it goes on and off and your can feel the vibes.
Could it be accidental pressure if it only happens in your pocket?
Hmm! which pocket, can you try another, is this a trouser pocket? 
You could borrow someone’s phone to see if it a pocket problem? 
Apologies for the silly ideas, I’ve brought tears to my eyes, but they are relevant questions.