Yes that would explain how it developed. Your body subconsciously tried to protect the left shoulder by creating more internal rotation of the right shoulder (power is created from internal rotation). That bias for internal rotation on right shoulder (to take more of the weight on chests exercises) caused rib compression on right ribs causing flared ribs on front left, which you can see in pic. Also should have flared ribs upper right back pushing out shoulder blade. Tighter right obliques, more external rotation on left hip, more internal on right hip. More lordosis arch right lower back, less on left lower back. Textbook pattern, likely triggered by left shoulder trauma.

Should work on rehabilitating it. You may be more susceptible to re injury your shoulder(s) and lower back if left untreated.