We also don't know if Saddam, himself, or his sons didn't order that stuff unsealed and moved somewhere. We know that Zarqawi was already in Baghdad and Saddam knew he was there and where he was located.. wouldn't have taken much to say -- "oh by the way" -- as we rolled into Baghdad.
I'm not denying that the Administration probably knew about this and if there is one thing ALL administrations are famous for is keeping things quiet when the truth would do better --like Oklahoma City Bombing, TWA800, etc.. the collective group of them need to learn that we would trust our government more if they leveled with the public.
To follow up on what you said, we were told by people in Baghdad that Saddam basically threw open the doors to all of him ammo bunkers in the days leading up to the fall of Baghdad. There's no telling where most of the munitions went before we got everything secured. There were also several instances while I was there of looters blowing themselves up trying to steal stuff form stuff we had secured.