Leaking something from my nipples!

After I removed my shirt to get in the shower last night I saw my bra in the mirror and noticed a dark nickel sized spot and when I touched it it was dry, then checked my left boob and my bra had the same thing, tried giving my nipples a little squeeze to see if something would come out and nothing did, but googled it and it said nothing to worry about, however I am 8 dpo and don't know if I could possibly be pregnant which is why that happened. It's never happened before that I've ever noticed, has this happened to anyone else and then they found out they were pregnant?