Don't freak out! My kids have them as well. My 3 year old was recently checked out at the Mayo clinic by a dermatologist for her birth marks at the urging of our pediatrician. I think pediatricians are quick to sound the alarm and send you to a specialist so they don't miss anything. The dermatologist said the only time they get concerned is if the spot is very large, like over 1/3 of their back. My husband has had skin cancer numerous times, including melanoma. The dermatologist said there is nothing to worry about with the kids. Just lather up the sunscreen. So, take a deep breath.