I’m guessing there’s nerves there. I’m not really sure though. I pretty much have it down to a science now to where I hit myself In spots that are completely devoid of feeling. Like I don’t even feel the needle break skin. I always go pretty slow though, and I think that helps. I know some guys just smash it in like a dart, but I’m not all about that life. Going slow if I feel myself hit a nerve or some thing I don’t like I can re-adjust my aim or just hit a new spot.