Sixty times per hour it resolved all three and sent http requests to all three.
I assume it was a simple connectivity check, but using those three domains was worse than redundant, it was gratuitous. They all resolve to the same IP address, same NS record, and connect to the same service on the same server. The only scenario I can conceive of that would cause the second or third test to differ from the first is if the IANA borked one of their registrar records.
Anyway I got the thing to read me a book during LASIK recovery and unplugged it within a week after the third time it piped up out of nowhere. (Nothing like waking up during a deep sleep in a quiet house to a blaring "SORRY, I DIDN'T QUITE CATCH THAT.") Maybe someone who didn't have that problem can let us know if the device is still doing this.