If it helps you feel better, the first positive zap test I ever had was because my stick blender burped and I got fresh batter on my lip. Then I instinctively licked it before realizing what it was and ran to the sink. (Thankfully I reacted fast enough and didn't have any burns)
Oh, I'm sorry to hear that, Kittensmom! I sure hope your tongue is getting better quickly.
I've learned to zap test cautiously. I always put a tiny smear of soap on my finger tip and very very gingerly touch my fingertip to my tongue. If the soap is zappy, it's not likely to be a big mule kick of a zap when I do it this way. And I always stand near the sink so I can quickly rinse and spit if needed until any zappy sensation is gone.
I've also learned to not zap test until after I'm pretty sure the soap isn't zappy. I know that sounds kind of pointless, but when used like this a zap test is a final confirmation of safety -- a double check that I'm right that the soap has no excess lye.
The only exception to the rule is when I zap test during a soapy experiment. Then I've gotten a few mule kicks, but I've asked for them.