Welcome to the land of RBBBs. I also have one, detected at my first ECG for my class 2 at age 40.
An RBBB can is caused by some sort of 'miswiring' in the nerves in the heart that transmit the signal to beat. [please excuse a laymans understanding and language]. It can be caused by an underlying heart disease, but much more frequently it is harmless and benign. Quite often there are no associated symptoms which is why only the ECG detects it. I had to do a set of 24-hour egc, echocardiogram, and exercise ECG to prove that mine was indeed harmless; I assume that you'll need to go through the same. Note though that this condition does not 'go away' and is not caused by 'white-coat-itis'.
Good luck.