Salt sure is cheap... isn't peace of mind worth a few bucks to you?
I remember a local club member sharing that he used tap water and salt for his first salt mix. After learning why that was a horrible idea, he was wishing he hadn't done that. He started asking about carbon, Phosban, etc. to correct the problem. The answer ended up being "We're talking about $10 in salt. Throw it out, start over" which made a lot more sense.
This hobby's way too expensive to let $10 stop you from being SURE you're doing the right thing. While the salt may be fine, you're certainly not going to see anything wrong with a visual inspection if anything IS wrong. And, salt, like RO/DI water, has a way of absorbing stuff around it.
Just my two cents.