Not sure what could have happened to it to cause this. As my shoulders have popped in many moves but never causes any pain. I wouldn't be too worried, but if the pain doesn't improve in the next couple of days you might want to get it checked properly. Also don't do anything too painful at the gym. If it hurts tell your coach and don't make it worse. These are the rules my mum uses with injuries. If it's really serious, straight to minor injuries, or my coach will have called an ambulance ( only happened once) and then less severe injuries go to minor injuries or doctor if no better in a few days or worsening pain.
