Cool!
Yea, it's pretty typical for the smaller bucks to carry thier headgear for a bit longer (not just in the Yakima area). The antler cycles (growing, velvet shedding, dropping antlers, etc) are caused by fluctuating testosterone levels...the little guys just don't have the strong "kickers" that trigger it like the more mature bucks do. Of course, just like humans, this isn't the case with every smaller buck but it's pretty typical.
The same thing goes for bucks that are past thier prime in a lot of cases and those levels begin to drop again.
(If I am off-base on this I am sure someone will chime in. It's been a while since I studied that chapter...LOL)