It is completely normal for the area around your incision to hurt. When you had the c-section, the doctors literally tore your abdominal muscles apart.
That's actually not true, must c-sections only move the abdominal muscles to the side-- there's no cutting or tearing of the actual muscle. It is true that you could have a lot of built up scar tissue, though. Depending on the severity of the pain, it might be worth a mention to your doctor at your next visit. It is possible that the scar tissue attached somewhere it shouldn't have, which can definitely cause discomfort.