Great photo. You were lucky to see one in the log like that. I was there for two days and they were always up by their night cage. Only saw them come down once, and they walked around so fast I couldn't get a good picture before they went back up.
My Pallas Cat photos from CMZ are by far the best ones I've ever had of this species. The animal's resting position in the log so close to the glass was like a dream come true. How you described the Pallas Cats' behavior on the days of your visit applies to my experience with the Amur Leopards. Their enclosure is as photographer-unfriendly as any enclosure can ever be, and I have no photos, neither of the cats nor the exhibit (there was just nothing to take photos of). But less than two weeks later I went to Minnesota Zoo and got some outstanding shots of their leopards, I almost couldn't believe my luck. Snowleopard complained about that exhibit in his 2008 thread but I found it very easy to view and photograph the cats in it.
I really enjoy the Tiger and Pallas Cat exhibit but the Snow leopard and Amur Leopard exhibits were generic like most zoos big cat exhibits. I do believe there way better than Denver's but if I remember correctly the Amur's was a small cramped cage that traveled upright.