Now what could have caused this?

The peaks around August 5 are due to the release of XRay 1.1. The peak on August 23 seems to consist mostly of accesses from IP 63.227.76.25 (no hostname resolved) to this weblog.

Hm. Maybe it was a comment spam robot trying to figure out how to post here? I had to delete 3 or 4 spam comments on that date.