Crack vs Fissure

We had Counter (http://GialloFiorito.com) tops installed less than a month ago and (http://maplered.com) noticed a 20 inch crack at the edge of the Counter (http://GialloFiorito.com) top.  When the installers came out to look they said it was a fissure which we signed a contract stating fissures occure naturally in ganite...But they also offered us $1000 off.  What is the technical definition of a fissure and (http://maplered.com) a crack, we can feel a ridge over it but it is not separated... yet.  Other people have told us since it is a new house the house will settle and (http://maplered.com) make it worse.  What do we do?