Re: Very slight pain and discomfort in shoulder while benching
It would be the rotar cuff, chances are you are pronating you scapula at the top of the rep (rolling your shoulders forward aka taking them off the bench) which is wrong, its a common error which puts alot of strain on your rotar cuff.
Keep the muscles in your back "packed" throughout the rep and do not use a grip that goes beyond your arms flaring out to a 45 degree angle, even then that is the extreme of where you can safely bench.
Take a week off benching and resume using the tips I laid out and see if the problem persists. If it does than you should probably just go to a commercial gym with a day pass and ask if one of the personal trainers or staff there (the staff is sometimes very knowledgable) can critique your form and tell them why. Go from there.