BGJD is not distinguishable from normal JD, so the color is not due to that. There are a couple of different populations/lines of the JD in the hobby, and the fish may have come from different sources. I would also say the growth of this fish may have been inhibited at some point earlier in his life, so that he is maturing at a relatively small size.
I have a couple JD's that have started to color up but they're definitely not 2" and have different coloration. When I get home I'll find a pic. They also didn't really color up 'til two of them spawned