Erik, just your second time.
Was your first use successful? Good, let's try an understand what might have gone wrong.
On this second occasion did you set the temperature and time manually or remotely? I recommend you perform manual settings until you have confidence gained from several successful cooks.
You are embarking on a very different cooking method that above all requires a detail-oriented approach. To begin, sous vide is the commonly used name of the cooking technique you are attempting to use. Is sous vide also the name you've given your new Anova Precision Cooker?
I call mine Cosmo.
As i understand, you were cooking something at 60C and after 45 minutes your Anova sounded its intermittent finished signal, - not a steady tone, that's its alarm.
Did you set your cooker's timer for a 45-minute cook? You write "desired 60C temp." Do you mean that was the precise temperature setting on your Anova cooker's control interface?
At the end how did you know the water temperature was 66C?
Did you verify it with a thermometer?
Or was the actual water temperature (upper reading) on your Anova's display 66C even though the set point temperature on the display at that time was 60C? (lower display reading)
As i understand the Anova's operating system, that should be impossible.
What was the temperature of the "preheated water"?
Did you add more hot water during the cook?
I regret asking so many questions, but without a solid understanding of your experience with your new cooker it is difficult to assist you.