Your pH was not 3.2. It's simply not possible just from several tsp of minerals; you'd have to add a LOT of actual lactic acid to get to 3.2. 5.2 perhaps, but 3.2 no way, no how.
By the way, you should never ever ever use minerals to adjust pH. Minerals are for taste. Use acid (lactic, phosphoric, or acid malt) to adjust pH.
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As to never using minerals to adjust pH, I would caution that making the right water starts with salts and ends with acids, because you want to hit the right composition of the water for the style via salts (typically), but then you need to dial in the pH with some acid, if necessary (often very little is needed and perhaps, though rare for me, instead a slight bit of alkalinity is needed to hit the mark).