Wow, Kashta. So the ice cubes may have made the difference. You know I would have thought that the fish were too small to be exibiting mating behavour but seeing is believing!
I would say -yes- about the ice making a difference. And even juvenile goldies will display some sort of courtship behavior. They're still too young then to figure out why, but they still do it... much like pre-teens dealing with emotions and impulses they don't quite understand yet. The good thing about this is it gives you an early indication of gender. This early behavior isn't truly accurate, though, but it is fairly common and gives you a good general idea which sex the fish will grow up as.