Keep in mind that on many cars A/C will kick on on defrost or if the system wants to dehumidify.I'm not so sure if it could be the AC since the noise is produced even with the AC off. It does it sometimes with remote start and neither the power steering or AC are being used.
What's the history of the water pump on this car? I wonder if it's early indication that it's gong. (Since it seems to be a common failure item on the Cruze.)