Those colors are 100% original, absolutely guaranteed with total certainty.
I think you're picking up on the fact that the guns are in the low 9000 serial number range. Colors from that period can appear richer and bolder than the colors on earlier guns - say from the 4-7000 range.
Of course, earlier guns have had more time to age, mellow, and be used. These 28gs have barely been handled, and they've always been stored away in their case.
Here's a pics of 100% absolutely original 12g Boss O/U from the 8000 range:
OWD
