that would be the sale date, it may have been on a shelf for a year before you got it.
warranty is good tho, they pro rate the cost of a new battery, the newer it is the less they charge for the new one.
you may also want to unplug any phone chargers or radar detectors and stuff like that, if the little led is on its still drawing power. and can kill a battery over night when its cold out. or if a light is left on over night.
some times trunk lights dont turn off or glove box lights. and you dont know it.
