I don't have data or concrete evidence, but this is the innanet and heresay is good enough right?
Just a quirk but piebald starts to show up the more domesticated something becomes. Look at farmed whitetails over a few generations....
Not that that moose is domestic...its just an aberration....
Inbreeding or line breeding will often bring out rare traits, usually bad ones. I have 2 sisters-in-law who raise German Shepherd show dogs. While they don't inbreed or line breed, it's almost impossible to get quality breeding stock that isn't. GS show dog lines have all kinds of serious genetic traits. They've both had to put down a lot of pups with problems.
Moose have a much smaller gene pool than, say, whitetails. I can see how a bad trait would have a good chance of being propagated.