I know the feeling; I did it when first starting out a couple of years ago, BUT added insult to injury.
I had a cycled new 55, my yellow labs and blue cobalts came in, were maturing, growing, etc. etc. I wiped up TESTING KIT fluids--just a few drops--and instead of putting the sponge back in the "danger" bucket, left it sitting on back of hood. Next morning, every one of my fish were dead, overnight!!! I looked all around, scratched my head, then looked again and saw the d***n sponge bobbling around at the filter out take. What a total noob!!