no its defo something to do with the head. it does run rough on idle a bit put you can hear the tapping loud from the rockercover , i think its a sticking tappet , as when its idling and it runs rouch for a split second you can hear the tap as if its gone back to position if that makes sense!
i just give it and oil change and put in some oil treatment so hopefully it might dissapear if its a sticky tappet