Had laparoscopic gallbladder surgery six months ago. now have pain in belly button. could this be an adhesion??

No, the term adhesion means the peritoneum (membrane layers in the abdominal cavity are stuck together - adhere) not the bowel is stuck to your umbilicus (belly button). Your pain could be a nerve pain after a previous surgery (a superficial nerve was damaged with the cut) or with the navel problem by itself, we can only say for sure after a physical exam.