Unused Payees gone after a period of time - like 6 months ?

I've noticed this for a while now and it's been really bugging me, but tonight I need to ask, why are my payees disappearing after about 6 months? It seems like if I don't use a payee for more than 6 months, when I go to enter a transaction, they are gone from the list. Is there some clean up function I'm not aware of? This is quite annoying. I can go back in time and see the payee information, but the payee doesn't populate when I am adding a new transaction if it's been more than 6 months since I last entered a transaction with the payee information.