As many of you may already know, Jack Daniel's has a program called “Buy the Barrel” from the distillery. Those (lucky) customers go to the Jack Daniel's distillery and select their barrel. But before doing so, samples are drawn from the Single Barrel stock and presented to them where they're able to taste and then finally select the barrel they prefer. Jack Daniel's will process & bottle the selected barrel for the customer and it will be sent to a distributor or liquor store in the customer's area for pick up. The customer gets to keep the bottle of the sample whiskey of the barrel they selected. Since the sample whiskey has not been processed yet and instead is only a sample drawn straight from a “Single Barrel” barrel, it is put into a plain, unlabeled square bottle from the lab. JD's lab has a form, which is blue, they fill out on that particular sample of whiskey that gives various information. Normally, the blue form is rubberbanded around the bottle and sent on to the selection in that manner.
Your question about blue label, is someone that has seen a bottle from someone who has purchased one of Jack Daniel's Single Barrels.