I seriously doubt that Oskaar. I'm well aware that I should have used Go Ferm and Fermaid K (which I have now, and will change my nutrient procedures in my next batch of mead). I don't think that the 6/7 tsp/gallon is excessive though. The brand I have recommended 1 tsp/gallon (carlson yeast nutrient, urea/diammonium phosphate blend) and I have used the same procedure in other meads and not noticed the saltiness in the must during pitching, or well several months into aging. I didn't taste my earlier meads at the end of fermentation since I had actually forgotten about them (hehehe).
I just did a taste test too. I took a tsp of nutrient and cut it in half 4 times till it was 1/16th of a tsp, and added it to a cup of tap water, stirred well and guzzled it all. I would be hard pressed to tell the difference with an ordinary cup of tap water. I also tasted the dry nutrient and can say that the type of saltiness is different. The saltiness in the mead is more of a sharp, acidic NaCl variety. It tastes like someone mixed sea water with mead and kerosene. Much stronger than the nutrient could possible account for.
I suspect it is some sort of acid produced by the yeast that tastes like salt to me, but I have funny tastes.
edit:
I was just thinking... if its from sodium or chloride, where are the ions coming from?
Then I remembered, my tap water is chlorinated and the chlorine might not have completely degassed. Is this a possibility?
2nd edit: I'll note that I also used only 1/4 tsp of nutrient in 4L of the watermelon melomel, and the liquid in that came exclusively from the watermelon, so tapwater nor the nutrient can be the culprit here.