Okay, So I Have A Son That Is 9 Months

Okay, so I have a son that is 9 months old. I stopped breastfeeding after the first week because I wasn't not producing enough milk. I haven't been pumping or anything I dried up long ago. Well, my breasts were feeling tender today and when I squeeze on the nipple I get a drop of milk. To add to this my son was a c-section and I got my tubes tied right after before they stitched me up. Why do you think I would have these symptoms 9 months later after drying up?