The tracks (if they were there-which they are not) would have coincided with the reduced patterning, 50% offspring ratio, slightly brighter coloration, and large head stamps to suggest Orange Dream.
Orange dream in a low expression form is not obvious and the gene is widely being used as a pattern reducer/color enhancer in all sorts of projects. From the photos: Neither of the parents appeared to have orange dream--so it would have been a head-scratcher if that was the case.