Depends on which batch you got your LCD2's from. Early LCD2 rev 2 that came out straight after late rev.1's have a high crack rate. I cracked my late rev.1's on purpose (whilst modding so it was my fault), easy to fix, gives me a excuse to have finally sanded it down, applied a single coat of Jarrah oil stain to deepen the colour and just applied the first coat of polyurtherane today.
Bit more than just 10%, more like a good 20% of people had there's crack from the rev.1's to the rev.2's from the original LCD2 thread that ended up being locked to this one. It wasn't until they introduced bamboo and the metal connectors we stopped seeing rates of cracking.
...lol that is a bit unsettling. I've been using mine for several months until i realized that there was a cracking issue for non angled. Atleast the odds are with me if u say 20%. Btw do you know if the crack effects the sounds of the headphones (or make it dysfunctional) or is it just a cosmetic marring that makes it look unplesant.