this my friends is nerve damage.. at least it wont affect his score in the symmetry round! (if he entered contests 
)
I googled pectoral nerve damage. This seems to be the most relevant finding. According to this, training makes it worse:
Department of Plastic and Reconstructive Surgery, Innsbruck University Hospital and Ludwig-Boltzmann-Institute for Quality Control in Plastic and Reconstructive Surgery, Anichstrasse 35, A-6020 Innsbruck, Austria. alexander.gardetto@uibk.ac.at
We report on two cases of isolated damage to a muscle branch of the lateral pectoral nerve. Diagnosis was established by the clinical presentation and electromyographic examination. In the few reported cases of such injuries, the cause was trauma to this region. However, in both of our patients, focal muscle atrophy gradually developed after initiation of training schedules to increase the cross-section of the major pectoral muscle; we therefore assume that compression injury to the nerve by repetitive muscle contractions may be of pathogenic relevance. Anatomical studies of this region showed that the nerve branches of the lateral pectoral nerve, having to pierce through a connective tissue septum that is thicker here by a few millimeters, may be subjected to additional risk of compression. Early recognition and treatment are vital to prevent associated morbidity of these rare but serious injuries.
