Pectoral minor dominance is usually related to 2 things-

1. anything cervical. If you have cervical pain, issues then the Pminor starts taking over since its not linked to the cervical spine directly and the brain recruits it for more tasks in moving the hand.

2. posture. all of us who work on computers with hunched shoulders and infrequent breaks will have some amount of pec minor dominance especially on the dominant hand.

question is what amount of stretching works, is safe and dosage, i.e. how many times per day etc. there is a point of view that instead of stretching, one should just practise "relaxing the muscle" but in my experience stretches do help more than just relaxation methods.