Dpo 5 bleed-anyone else??

First month TTC-had a random bleed on DPO 5. It was like period blood (not what implantation bleeding is described as on the web) and thought I got my period early but then completely stopped and no blood DPO 6 all day... what could that be?? I have a feeling no conception... did this happen to anyone else? I read it could be an estrogen surge but this has never happened before.