Considering Iraq was making binary mustard and nerve agents, I hope you are right. They had considerable stock piles of mustard and sarin that were produced after the war with Iran. Binary configurations have a pretty long shelf like, far longer than unitary. Iraq spent considerable time and effort refining both. Most were placed in artillery shells, perfect for IED use and easily transported.
During their war with Iran, Iraq was only producing short lived, unitary nerve agents and mustard. It is highly unlikely these are left overs as they would have been destroyed due to their short effective lifespan.