Hi Ed- Our flight was more than 72 hours, but within 3 calendar days. We had no issues. However, I understand you want to be certain you have no issues.

From the CDC website:
Why does the Order specify 3 days rather than 72 hours? What is considered 3 days?

The 3-day period is the 3 days before the flight’s departure. The Order uses a 3-day timeframe instead of 72 hours to provide more flexibility to the traveler. By using a 3-day window, test validity does not depend on the time of the flight or the time of day that the test was administered.

For example, if a passenger’s flight is at 1pm on a Friday, the passenger could board with a negative test that was taken any time on the prior Tuesday or after.