Yes, that murmur is common enough among athletes. For military EKG's, they would have us do pushups first to get the heartrate above the rough low idle, just to get a cleaner EKG. I still do that for FAA EKGs.

As of now I think you have to report the visit for the virus. You don't have to talk about any EKG results if the doc said they're normal.

If you go to a specialist, you'll have to report that and explain why. But if you have any doubt about your health based on what the doc said, you should follow up. Can't hurt, since you're still in training.