Why Does One Have A Long Mark On The Breast?

Hi, I had a core biopsy on my left breast Jan. 21, 2011. The results came back benign which I am grateful for. However, I just noticed a long mark on the same breast. It feels like a needle is in there. BTW I have never had a lump in my breast and the Dr. only decided to do the biopsy after my annual mammo. Is this common or should I consult a doctor?