For the cost-conscious health-care consumer, even those seemingly free annual checkups or well-child visits call for some caution. Dani Roelker, who lives in the Cincinnati suburb of West Chester, found that out the hard way. She took her 10-year-old twins to their pediatrician's office in January for their annual wellness checkups. A few weeks later, when she returned to the office for another pediatric visit, a worker told her that she had an outstanding bill of about $27 for what Roelker had thought would be a free visit. Roelker said she was billed because a nurse asked about her son's attention-deficit-disorder medication, which had been first prescribed in October and had been checked during a follow-up visit in November.