missing money

The way our office works when we bill medicare is that the money goes to the patient and it is then their responsibility to bring it in. It's complicated and boring to explain and not so important so I'll move on:
Today a very old patient brought in some medicare money. I opened her account and looked at the medicare explanation of benefits and got very confused until I looked more closely at the date... December 2006. I told what I assume was her son this. He asked her, "Have you been holding onto the medicare money?"
She said, "Oh no I always bring them in right away."