The battery can not get "newer." So its possible that the battery's overall life may be shortened. How much the battery differs from a recently manufactured battery would depend on how the battery is stored. Most likely it was stored "correctly" and probably will work just as well.

Most Li Ion lights use circuitry that keeps the light as bright as possible for a given setting. When the battery fades, usually the light just completely shuts off.

If you only use your light a little bit, you should buy lighting setup that includes a recently manufactured battery. Otherwise it doesn't matter