WebContainer Close Event Raising Nil Object Exception

When a user closes the browser window it triggers a whole chain of close events as it should. When one of my embedded containers receives the close event it attempts to perform a little cleanup. (unlocking a database record lock). In this case its a call to an app-level method to perform the record unlock. I have been getting a NilObjectException when the close events attempts to call the unlock method. The two variables I pass to the unlock method are properties of the container. One is an integer and one is a dictionary. Is it possible the container’s properties have already been released from memory at this point?