Some Pigment Left Behind After Mole Biopsy

If a shave biopsy was performed on the mole, there is a chance for the mole to grow back.  I would not be too concerned with the pigment returning.  I would still have the mole evaluated by your doctor.  

It is quite common for there to be pigmentation after a mole is removed or for a mole to re-pigment later.  The important question was what was the initial biopsy report.  If it was something dysplastic or the mole looks very atypical now then I would recommend you finding a board certified dermatologist to evaluate the mole and perhaps have it removed again.  Your health is most important in these times.

Some recurrence of pigmentation after a shave removal of a mole is very common, and usually nothing to be concerned about.  The pigmentation is often somewhat irregular appearing.  Since it was benign after the initial biopsy, it is unlikely to be dangerous, but I would still have the mole evaluated by a dermatologist.