I bought flax seed at the local GNC, and have a question. It looks like it's already ground? It says "cold milled" does that mean ground? Or do I still grind it?

I used it as is once in a protein shake and it was pretty gross. I figured I would have to grind it (more?) to make it more palatable, but we lost power here before i could try that. I ended up having to throw it out when it went bad (power failure for 4 days) so I have to buy more....but do I grind it? or does this sound like already ground? Is that why it went bad so fast?

Also....just thought about this. People say they use a coffee grinder? Don't you have to be really careful clening the grinder after? of do you just have to wipe it out?

Thanks
Cindy