All of my Litespeeds with the yellow lettering cracked over time. I think they all do, I've seen others. It's just the age, or the sun?
My Ghisallo has the newer black and white letters, the decal is different. It has 6,500 miles in the summer sun and it's fine.
My guess is they changed the decals somehow. Just a guess. Maybe the fact that on painted bikes the decals have clear coat over them, helps protect them from drying out, or aging ???