Hmm I misunderstood your first question a little bit. The pop can't be felt in the handlebars, it's just a sound, but I can feel it travel around the headtube/upper fork. There's no impact on steering, or any stiffness/play in the headset. I checked the bearings today and the lower one has two distinct gritty points when I spin it. I'm going to start by replacing that. I'm a mechanic (2+ years) but by no means an expert, so if the replacement bearing doesn't solve it I'll consult the more experienced guys at my shop.