Any ideas? Has this happened to anyone?

Hey ladies! My husband and I have been trying for one last baby for almost 2 years. We never had an issue getting pregnant before but I’m now 40 years old. So we aren’t sure. Anyways, this month I ovulated and we did baby dance. However, I never spotted in the past that I can remember and I’m supposed to start on Saturday according to my app. However, I spotted for 3 days and then it stopped. It was never a heavy flow or anything only noticed when I wiped. Could this have possibly been implantation? I will include the calendar that has the three days highlighted when I spotted and then some images of spotting.