:) To be honest, it would have probably not been too hard to sort out... I just have a huge task list so I had been putting it off. This really got to the heart of the matter and sorted me out!
OH, if you specify a cipher key of an incorrect length, you will get a big stack trace when shiro tries to create a remember me key. Buried within the stack is a message saying it. At first I had no idea why it failed, but the details are all there in the stack trace. I ran into this, the test hex key in the shiro docs is of the incorrect length, I had created a new key of a correct length.