Got the car back from the dealer today. Turns out it was a leaf in the fan, however the way the service tech explained it is that the fan is more like a dyson fan in that it's cylindrical with the fan around the outside. I guess that's why a leaf doesn't get shredded and just stays in there and makes a constant noise.
I also can't quite figure out how a leaf would get past the filters, but it sounds like it happens, so I may look into a very fine mesh to put in the intake under the hood to keep large debris from even getting to the filters.
They also tried to charge me over $700 dollars to remove some leaves....so there's that.
Even in Hawaii I have found leaves in my A/C inlet, some of which made slight noise. I bought a conversion kit from Amazon that allows me to use my Shop Vac to use a very small, long thin, nozzle that enables me to reach through the inlet guards and the "fins" (when raised in the open position). I used that method to vacuum out any leaves stuck against the condenser. But it got to be a pain to do that at least monthly or when I heard a noise.
Then, based on the scary reports of the A/C problems (rock damage to the condenser with subsequent costly repairs) and following the always invaluable advice from "AlohaArt", I ordered some black flexible wire mesh (1/2 inch openings) from Amazon, measured and cut it to fit over the "grill", and secured it with some flexible black twist ties (4 hours work). It is not really that visible at all and keeps out the leaves as well as rocks/stones.
I kept a careful record of the battery temps during the last 9 months of the "mesh" usage and even in the summer time with high heat, the "mesh" does not affect the temperature (or A/C temp) so enough air is certainly passing through to cool the condenser.
I did spend 10 minutes removing it prior to taking it to the dealer for the "2 year" service last month just in case they might look askance at the "mesh" and claim some sort of "after market" alteration on my part. Then it took 10 minutes to re-attach it once service was completed. Cheap insurance.