I agree with BionicBabe - definitely get him looked at for safety sake before letting him practice or play. It could be nothing or something but when you see
young athletes with debilitating heart rhythms you worry about WPW, ARVD, hypertrophic cardiomyopathy, coronary artery abnormalities or, to a lesser degree, idiopathic arrhythmias. Except for coronary artery abnormalities you can go a long way towards ruling out these problems with an EKG and echocardiogram.