Posted: 06/06/2012 at 21:59
They are a spring flower and should die back to nothing soon, returning next spring. They will have been planted very shallowly in their pots, but the corms need to have two inches (5 cm) of soil on top of them, so you'll need to re-plant them deeper when the leaves have died back. The conditions that you've planted them in sound fine, although they don't need such sharp drainage.
So, nothing to worry about - you've done nothing wrong.