when my son was about 2 he saw a new pediatrician
who said he had a heart murmur
and was all scary and dramatic about it. I was worried terribly until we changed clinics and the doctor told me that it was fairly common and he'd probably outgrow it.
he is 23 now and hasn't had any trouble and has not had the murmur for many years.
I'm not saying you shouldn't keep an eye on it, or that it couldn't become more serious, but I think the odds are on your granddaughter's side that she'll be just fine!
doctors should remember how frightened parents will become when they don't get all the information. the doctor who found the murmur never told us it was somewhat common and that he could outgrow it. she let us walk out of there scared out of our minds and said nothing to balance the picture. shame on her!