heart murmor

during the visit with the anesthesiologist, he listened to mark anthonys "engine" and said, "you know he has a heart murmor?"
umm, no!
he told me that he does in fact have one, he can hear it.
"should i be concerned?" i asked, knowing that no matter what his answer was i would worry.
he told me i should mention it to his pediatrician at our next visit so she can monitor it, but that it seemed to be beneign, and it didnt seem to be bothering him right now.
SEEMED TO BE BENEIGN??
MONITOR IT??
not bothering him RIGHT NOW??
so that leaves the possibilities that it could NOT be beneign, that it could start bothering him at any time, and that his doc needs to be watching it??
course if you know me well at all, you know my mind is racing, thoughts swirling, heart pounding.
what really bothers me, is the question...why has this not been discovered before now? its not like any of my kids are three-times-a-year-doc-visit kids. we are more like once-or-twice-a-week-doc-visit family. he has seen 3 awesome pediatricans in his almost 3 yrs. he has seen several specialists. tons of nurses. they all listen to his "engine". every time.
mark tells me not to worry, its very common, tons of people are walking around every day with heart murmors.
but my kids arent supposed to be in that group!