I was just wondering if anyone thought this might mean anything.
Personally, I suspect you just dropped a couple of the stones.

Obsidian is usually pretty smooth and can be slippery, since it's a kind of glass.
One note of caution: Salt, especially salt water, can badly damage some stones. There are other cleansing methods that are better for the stones, but it's a good idea to become familiar with the physical characteristics of your specific stones. Sunlight can cause some to fade or lose their color completely, and even plain water can dissolve some stones.
A lot of people who work with the metaphysical properties of stones recommend cleansing them by putting them in contact with selenite, ideally laying them on a large piece of selenite and leaving them there for a day or two. I have no opinion about the efficacy of that method, but at least it won't damage the stones.

~ Aster