My Herringbone Spider

I looked up a moment ago to see a little spider high on the wall here in the office, and was happy to see that it was this guy (gal?) again! He (she?) keeps coming around. I first saw it in the kitchen on May 23d. Then about a week later, I found it in the kitchen again, but this time sort of fastened by webbing onto an old receipt that tucked into a bowl on the counter :


The spider was under the web, not on it, and it seemed quite immobile. I showed it to Hugh and then put it down on my desk, and later the spider was gone, only to be seen again later that same day over on Hugh's desk:


Its head is a little blurry, but you can see how the back section looks sort of rubbed off in the middle and more orange on the sides than it was before. It's such an unusual spider—I've never seen one before, unlike some kinds of jumping spiders which are all over the place—that I can only think it has been the same one every time. What was it doing under all that webbing?