It should be fine. Here is a couple of ideas to get it back to a fine crystal form. 1) Use a flour sifter. This will take some time and effort.
2) Put it in a Mixer and turn it on for a while. This one was my wifes idea she said it worked of powdered surge.
Or just through it in the bucket with you RO/DI water and make sure it all gets dissolved.
I hate it when my salt gets clumpy. :evil:
Alan