Hey guys. I was working out today (I'm back from about a 5-6 month break due to a back injury) and was working shoulders. When I do rear delts I like to lie on the incline chest down (so I'm laying on my stomach on an incline) and squeeze back nice and tight with really light weight. Well I was doing this today, and didn't notice any pain or discomfort until I stood up and stretched out my chest and I felt pain (possible just from the pressure of pushing my chest into the bench) in the center of my chest like my ribs. This only hurts when I stretch out or flex my core. Any possible ideas? Is it anything serious or should I just give it a couple days to see what happens?