I am not an expert on the subject, but I think it is just one of those traits that can be more or less pronounced. It may depend on the catch location of the ancestors, or some recessive gene. For me it's the deep blue and greens that make the fish look so impressive, but those colors often don't translate well in photographs. Your impression is certainly more important and reliable than mine since you have the actual fish to look at. Here are a couple of pics of the first male I had which never showed any pronounced horizontal bar, just faded and broken patches.