Let me take a guess here.....Was rthe salt you had vacuumm packed in a polastic bag with the brand name of Instant Ocean all over it or just a plain platic bag with readily loose salt which moved freely in the bag?
Seems IO did make some changes on their salt and what you have is some old old packaged salt. I took this issue up with my LFS who did not belive me, and would do nothing about it except tell me I should have brought it back if I was dissatisifed........duh kinf of hard to return an empty box, but how do you return the salt when you used it to make a large batch of water up? ANyway I called the Instant Ocean folks... They were kind of generic in any rely, but the residue you see is NOT salt nor is it any trace elements as the individual that I talked to seemed to be implying. So I really never got what I consider a satisfactory answer but merely told it was still ok to use and will not affect salinity or water makeup ingredients one way or another, which is basically telling me its a inert filler they probably got cheap and decided to add it to the mix.......I still am not done with the residue issue as I do belive I have a right to know if I am adding stuff that will continue to build up and I want to know what this stuff is......I was told I had to talk to a certain individual, who was at that time not available to talk to so its on my list to do today and talk to him hopefully.
I also found out that there wa a large aquarium and pet supply distributor that went out of business, and a lot of their stock was sold off very very cheap to lfs......thats where my lfs got the salt I had from.
Plain and simple youy got old old stock .
