Old bottles?

FTM here, I got a sealed in the package brand new set of Dr. Browns bottles, with each bottle and nipple etc sealed in their own individual bags, on sale. They are the 2015 model. Is there any reason I shouldn't use older bottles, even though they're brand spanking new?

I will sterilize them before using. I know things like car seats have a "use by" date something like three years from manufacturing so I'm wondering if bottles do as well. Read the whole instructions and box and it doesn't say anywhere that they can't be used after a certain point. Thanks for any advice!