What Scott said is absolutely correct. In addition to it, there are a couple of things you would want to follow in retirement.
Maintain credit accounts: Do not close your credit accounts as it will affect your debt-to-limit ratio. By closing a credit card account, you're reducing your available credit limit. Further, lenders prefer borrowers with long credit history.
Thinking that your credit score no longer matters: Even if you're retired, you will require insurance or perhaps you will refinance a debt. That's when your credit score comes into play. It is best to stay financially disciplined even in your retirement.