You were, in fact, tasting the salt. The prevailing theory is once the blood hits the lungs, the extra molecules end up out in your lungs and you exhale them, causing you to taste it. I’m not sure I vibe with that theory. But I’m no scientist. I’d wager, though, that the blood passing the mucus membranes in your nose and throat causes the taste. But apparently even the medical establishment hasn’t figured this out yet.