I tried to get to the bottom of it, but I didn't find much. I did find an article that said food prices in general may be rising due to El Niño, so that may be a factor. Also, an article about general consumer dissatisfaction with higher pet-food prices: http://www.petbusiness.com/January-2016/The-Cost-of-High-Prices/
And, stats from last year that show that pet food prices fell to a fairly low point in August 2015 (which may explain why they're going back up now): http://www.petbusinessprofessor.com/petmarket/buying-pet-products-price-matters-petflation-update-and-more/
