Apparently a metric ton of WMD is not a 'stockpile' technically. I suppose we still need to apologize to Phil Donohue and Cindy Sheehan since we didn't find the entire 10,000 tons.
The 'stockpile' problem is another misnomer. Chemical and Bio agents are not the sorts of things that you'd ever want to have a very large amount pre-made at any one time. There are shelf-life issues, but more to the point they have some genuinely non-trivial management and logistics issues. It is most definitely not like storing ordinary high explosives.
Most of the time, you'd prefer to have only a relatively small amount ready to use, and make more as you need it. A little bit goes an extraordinarily long way, and replenishing is quick and easy.