Dave, you pose a really good question here.
My interpretation of generally accepted accounting principles is that if an event occurs that makes it probable that the company will incur revenue applicable to a particular period prior to the closing of the financial statements, it should be recorded in the year applicable. There are many objectives within GAAP and one of the most significant is that companies appropriately match revenues and expenses in an accounting period.
Companies routinely leave their books open past year-end to catch activities that apply to that year but are not known at the end of the year. The general rule is that if an obligation is owed, it should be recorded in the year the obligation is incurred. Conversely, if revenue is earned, it should be recorded in the period earned. If an unknown event is material to the financial statements and becomes known after the end of the year but before the audit is completed, then I think the company's auditor would require the transaction to be recorded in the year applicable.
Typically, auditors will require adjustments for events that become known between year-end and the last day of field work of the audit. Auditors are responsible for the review of events until the last day of field work which is the date shown on the audit report. Events that become known after the last day of field work in an audit usually become subsequent events in the footnotes to the financial statements otherwise audits would never get completed.