Dave thats called spidering usually caused by Hot water hitting the sink bowl( like pasta water draining in a culinder you know what I mean ). When I got certified for Avanite they mentioned this in the class, and it is best if cold water is ran to help cool the water down before it hits the serface.
solid serfaces have that problem with heat weather hot water or hot electric pans.
I'll see if I can find that in my class papers and post it.
Don
Got it
http://i43.tinypic.com/2hqwcaq.jpg