I have this as well although I am a 31 year old and outside of flying am a competitive road cyclist. My AME said it was normal for my demographic and required no further investigation. In short it goes to a cardiologist who will sign you off unless you have a questionable cardiac history or other risk factors.
This might be useful ->
12-lead ECG in the athlete: physiological versus pathological abnormalities -- Corrado et al. 43 (9): 669 -- British Journal of Sports Medicine
"Early repolarisation has traditionally been regarded as an idiopathic and benign ECG phenomenon, with an estimated prevalence in healthy young people ranging between 1% and 2%, and a clear male preponderance.The early repolarisation ECG pattern is the rule rather than the exception among highly trained athletes, in whom it is observed in 50–80% of resting ECGs"