I didnt have any dips on my chart, although I did start spotting early at 9 DPO and it continued for the next couple of days. I fully expected to get AF, but to my utter surprise at 10 DPO, I got my BFP!

So based on my experience, I would say that it sounds like implantation spotting, especially as its 8 DPO (not sure about your usual luteal phase though).

that it leads to a BFP for you!