What is wrong with putting Using Blocks in Repository

public IList<something> GetSomething()
{
   using (DB db=new DB())

   { ...GetListofSomethingElse(id)

   }
}

public IList<somethingelse> GetListofSomethingElse(int id)
{
    using (DB db=new DB())
   {
     ... return IList

   }
}

using( ISession s = theSessionFactory.OpenSession() )
{
    ICustomerRepository cr = RepositoryFactory.GetCustomerRepository(s);

    Customer c1 = cr.GetCustomer(1);
    Customer c2 = cr.GetCustomer(2);

    // do some other stuff
    s.StartTransaction();

    cr.Save (c1);
    cr.Save (c2);

    s.Commit();

}