Be careful. I had shoulder twinges from benching too much back in December, and it turned out to be bicep tendinitis. For me, when I would lock out, my rotator cuff wasn't strong enough to keep my humerus in my shoulder socket for the last little push. Doing a massive number of pull-ups didn't help. You should probably look into strengthening you rotator cuff some, and make sure you are balancing pushing and pulling exercises. If it gets worse, go see a doctor or a PT. In the meantime, when you are doing push-ups, try to keep you hands along the line between your nipples, that will put less stress on that part of your shoulder.
Interesting, thank you. Like many American children, I also threw some half a million pitches before the age of 18, all without any real knowledge of stretching, rest, etc. So I suspect my days as a real bodybuilder were over before they began. I have been kicking around the idea of a few sessions with a PT but have never done anything of that sort so I'm not sure where to start. I'll look into it.