I have no answer; I can only ... possibly ... confirm your experience.
Had the phone with me while walking the other day. Using world's cheapest earbuds.* Whenever I put the phone in my pocket, it would either skip a track or pause. I ended up holding the phone in my hand for the entire walk, as it was the only way to keep the music going. I had attributed the problem to the cheap-ass earbuds (or, possibly, the cover of the case doing the equivalent of butt-dialing on the "pause" and "next track" buttons on the lock screen). More investigation is necessary.
*They cost $2.99. I'd asked the lady in the store for something that would "get me through the next 20 minutes," and she was pretty sure they could handle it.