Melted chocolate is known to seize badly if it comes into contact with small amounts of water. Ideally, when wetted more and mixed, it should get better again, although I think I remember cases where this didn't work.
I wonder what would happen if the chocolate is supposed to be used in a cake batter afterwards. Has somebody had experience with this? Does seized chocolate bake into a nice smooth cake, does it create an unpleasant grainy cake, or is it somewhere in between? How much does the texture differ? Also, if there are noticeable differences, does it matter if the chocolate seized due to water contact or to overheating?