Image from MacGeneration.
Apple has updated their repair policy for their iDevice liquid sensors. The main part of the change being that "if a customer disputes whether an iPod with an activated LCI has been damaged by liquid contact and there are no external signs of damage from corrosion, then the iPod may still be eligible for warranty service."
This is likely in response to a lawsuit filed last year as well as the news we've heard in the past of iPhones liquid detector being activated even when devices were never exposed to liquid. This is because some areas actually have high enough humidity to activate the sensor, which is apparently nothing more than some tape that changes color when it gets wet.