I recently got a mole biopsied and there's pigment left after the shave biopsy. Is it normal to have pigment left over? (photo)

I noticed a small mole in between my buttocks a couple of months, 3mm, hasn't changed color or shape ever since I noticed it and I monitor it pretty often. A couple of days ago I realized the mole felt really dry and a layer of dead skin fell off. I got really anxious and went to my derm to get it biopsied. She did a shave biopsy and mentioned there's a residual pigment left but told me I shouldn't worry about it. I'm getting quite anxious and wonderingIs it normal to have pigment left after a shave?