Left side nipple leaking when pressed.

Hello I am 36 yr female. I have a stopped breastfeeding 4 and a half years ago. I had been to normal breast checkup and when doctor squeezed my left breast there was a little leakage (only when she pressed it) She asked me to get my serum prolactin test done and now the results have come and it's normal 7.79 ng/ml I just got my periods on the same day night and my periods are always on time, so no problem with that. My doctor says it's normal and no need to worry but when I ask for the reason why is it leaking when my reports are normal she didn't tell me anything So can you please suggest me why it could be or should I get to do any more test? They say 1 side leaking breast is a sign of something else Can u please advise I am really very much concerned