fetchByQuery and fetchAllAvalable methods return different Descriptions!!

We have an application where the user logs in and gets all the tasks assigned to him. This is done by using WFSession.fetchAllAvailable(). Another requirement that we had has an admin user re-assigning this task to another user by calling WFAdminSession.reassignTask method. When I re-assign a task , I make some changes in the Description property of the task using another methos WFAdminSession.setNewDescription.
The problem is, if i fetch the task using fetchByQuery method, it shows me the correct updated Description but if I use fetchAllAvailable it gives me old description.
Has anyone faced this before??? pls help…