[Zope-dev] Is this a ZClass/Propertysheet bug?

If I delete a property from a ZClass, the property still exists for each instance of the class (I can do a dtml-var to show it), but it doesn't show up on the management screens for either the class or the instance. I cannot add it back with the Properties tab - zope tells me that it is in use. New instances of the class do not have the removed property. I'm using Zope 2.2.2 on Linux. Is this behavior correct? -Paul