Breast reduction, numbness in left arm? 1 month post op.

Had breast reduction a month ago. Everything seems fine but I am numb on the bottom of my left arm (tricep area) , armpit, and the left side if my breast. I saw my doctor today and he asked if that was the side the blood pressure cuff was on. I couldn't remember. He said "hopefully" the feeling would come back. I am concerned that something went wrong and I am not really feeling reassured that things were going to get better. Is this normal? Do I have a nerve issue now? Thank you.