I know it's been a while, but did you ever figure this out? I just bought a small jug of the fertilizer from repotme and had the same thing happen to me!
What ever atmospheric conditions favored that...relented it seems. I haven't been shocked but once shortly after this posting. Were the demons exorcised from my bottle ?
Though it seems counter, this year has been much much drier than last year. I suspect that also means humidity is lower (though it was 68% when I went to bed last night (and turned on the AC for the first time this year)).