It's a tangent, but there's a good article on 2008 rice prices freaking out because of the same effect: http://www.npr.org/blogs/thesalt/2011/11/02/141771712/how-fear-drove-world-rice-markets-insane
Short version is that in a normal environment there is enough rice produced for everyone, but suddenly everyone worries that RIGHT NOW they need to buy all the rice they will eat ALL YEAR, and that causes problems.
The solution was really interesting too. Turns out that Japan artificially insulates it's rice farmers from foreign competition, but to satisfy world trade agreements they buy lots of rice that sits in warehouses and rots. People started negotiations to re-export that rice to countries with a shortfall, and as soon as the word got around that this might happen people went back to normal buying behavior and the problem evaporated without actually moving anything around.