Not recognizing someone who I thought I should have

Today, while I was working at a retail store, I was feeling a little bad because I didn't recognize someone who came to my register. I think that when she was at my register, I had a feeling that I knew her but I just couldn't place where and how and I didn't know her name. It wasn't until many hours later that I figured out who she was. When I used to live in my old neighborhood, I would take walks with my dog and I stopped and let my dog and her dog play in her yard. I remembered that they really loved to play together so we would stop quite often if they were at home.