Not pregnant nor breastfeeding, but lactating?!😱

I started my period this morning. As I'm sitting on the couch watching tv with my husband, I noticed some white stuff on my right nipple (No, I wasn't wearing a shirt or bra). When I checked it, it had the consistency of milk. I squeezed it and it came out a little more. Is that normal? I'm 23 and this is the first this happens to me. I'm a little freaked out!