A 1-week-old black infant presents to you for the first time with a large, fairly well-defined, grey-blue lesion over the buttocks bilaterally. The lesion is not palpable, and it is not warm or tender. The mother denies trauma and reports that the lesion has been present since birth. This otherwise well-appearing infant is growing and developing normally and appears normal upon physical examination. Which of the following is the most appropriate course of action in this infant?