It can happen. I had some of that when I was in my 20s before I had children even. Do you squeeze your nipples sometimes to see if milk will come out? I did for a few months now and then, after I weaned my son, told my doctor and she said to stop squeezing and it would stop. It did.
I'm perfectly healthy that way, so it didn't mean anything.
Rarely, breast secretions can mean that you are secreting extra prolactin hormone because of a tumor in the pituitary gland, but this is rare and very unlikely given that you were breast feeding recently.