Shave biopsy on mole done a month ago. Came back benign but it has repigmented. Is this concerning considering short time frame. Should I biopsy again?

probably fine. Most likely part of the mole was above the surface of your skin and the rest was below. If the mole was just shaped of the underneath portion of the mole was not removed andthat is why you can still see the mole. If you are very concerned you can return to the doctor and review the original biopsy with him or her.
Mole Biopsy. The mole that was biopsied has a deeper component that was not removed by the biopsy. There is nothing to worry about since the biopsy showed the mole to be benign.