Stockpiled Rice

The new Minister of Agriculture, Forestry, and Fisheries, Koizumi Shinjiro, has declared that he will release 5 kilograms of stockpiled rice in June at the 2,000 yen level. Several days ago, I opened a bag of 10-kilogram rice and started eating. I think it lasts for a month, so I hope I can get the stockpiled rice before we finish the bag of rice.  Well, I have a question. A couple of days ago, a member wrote about stockpiled rice. She wrote "stockpiled rice" in the title, but a corrector changed it "rice stockpile."  I'm not sure why it should be "rice stockpile." Is "stockpiled rice" incorrect?  I'd like to know about the difference.