K.R.
Yes,
My son is 12 now, but when he went for his 6 mos check-up they heard an abnormal heart-beat.
It was the scariest thing I ever had to do taking him to a cardiologist. They taped sensors on his chest etc and did the "cardiogram?" and he was perfectly fine.
I remember that he was on some cold medicine as he had a fever the week of his 6 mos check-up. This may have caused the irregular heartbeat with the decongestant in the medicine...
No problem with check-ups since.
Don't expect bad news. Dr. is just taking percaution.