On two different occasions my shoulder has "given out on me during my push day with moderate weight. Yesterday was on incline dumbbell bench with 70lbs. Pretty standard weight I use during a warm up and right in the middle of pushing I felt a pop in my shoulder and couldn't finish the rep. No pain and I was able to go back and complete my chest work out. On another occasion it happened on military dumbbell press same scenario non work set with moderate weight. Can someone tell me what is causing this and how to keep it from happening? Or maybe suggest a better routine. My concern is this will happen to me on a work set and I'll drop a dumbbell on myself and get injured.