Go to the manufacturers web site and see if they have the mounting instructions for the drain which would include precautions on over tightening. If not, contact them directly and explain your situation.
Ron

Search using these two words like this

Define: crazing

Today, I got this and more:
http://en.wikipedia.org/wiki/Crazing

Causing it was probably either a thermal stress or a mechanical one.

-david

I went to the web site for this sink. It's 1 1/2" thick on the bottom, so over tightening would be unlikely.
David's suggestion of a thermal stress sounds like the problem. Pouring boiling water into the sink without running water from the faucet to temper the heat could be the cause.
When I ordered a corian sink with a countertop, the homeowner was cautioned not to do the above without turning on the faucet first.
Ron