I have never seen such tiny tiger beetles before. The best match I could find was Cicindela terricola cinctipennis but I'm not at all sure. I'm basing that i.d. on comparison of the shoulder, middle band, and apical marks, but especially the small size. I don't think it could have been over 8mm in length which made photographing it very challenging. In fact, it was so small that when it disappeared into the shadows I couldn't see it at all. I pointed my camera in the direction I last saw it and got one photo. I was very surprised when I downloaded the photo to see that it was mating with another tiger beetle that I hadn't even seen.