There are two definitions of "blue moon" and apparently the more widely used "two full moons in one calendar month" is actually incorrect. Nonetheless, it dominates the popular usage of the term.
The full moon of August 31st was the second full moon of August, and hence, a 'blue moon' in the common definition. Mr. Fuzzy took his Sigma 150mm f/2.8 lens out and captured it rising, the blue moon over the Blue Ridge.
"Blue Moon of Kentucky" is the title of a fabulous 1946 Bill Monroe waltz. Mr. Fuzzy rather enjoys the original 3/4 time recording with Flatt & Scruggs playing and Bill singing.