Could this be implantation spotting /cramping?

Christine
Got my positive OPT last Sunday so if I am right I am 7 DPO. Today around lunch, I had one little spot on my liner and no more the rest of the day. Also, I have been mildly crampy like right before a period (AF due 9/21). I had been worried that stress would kill my chances this month since my grandpa died, but could this be a good sign?