I own two of them. Both work perfectly. One has (minor) cracks, the other doesn't. In any case, I don't think the cracks are really from the heat, it's just something about the plastic. They crack in exactly the places you'd expect, mostly around the load bearing screws.

I may have wrongly assumed heat because we mostly didn't touch them and used them for build servers. It's still hard for me to imagine it was anything other than the heat.