Yes it is. The key is proper storage. Keep it from moisture and temp extremes. Same for primers and loaded ammo. There was a hooey scare going around last ammo/component shortage/panic where folks were claiming that "the government has mandated the addition of chemicals to render powder and primers useless if not used before a certain date". Horse feathers.
i have been reloading for over 40 yrs have a couple of containers that are that old and still work the same as when new,,as long as they have been stored properly, ie,, damp areas,,no large temperature vatiations,, and in original undamaged containers,, powder should be ok,, open the container and smell it , as long as it doesnt have a bad strong smell as in rancid heavey chemical oder it should be fine, if in doubt, someone at your local gun shop should be able to help.
If it is bad you will know it because it will smell like ammonia. Trust me, it won't smell like powder at all. Store it low to the ground where it won't get wet, and where the temp stays consistent and it will be just fine. Also, every time I open my powder to fill the powder measure I smell it so I know how it should smell. Then when I empty the powder measure and put it back in the container I smell it again. TYhat way if it ever goes bad I know what it should smell like.