Music

so i have this problem with my new iphone 6s, it stop, forward, rewind on its own when playing music with apple earpods.

this occurs when the phone is locked! Black screen and i also noticed that the buttons can be pressed and act on the black locked screen sometimes

is it the hardware problem? Or iOS problem?

this does not occur when im using bluetooth earphones not sure if thats because there is no wire attached to or the phone is not being contacted by anyother objects