Crack after new installation on VOLAKAS MARBLE.

Crack after new installation on VOLAKAS MARBLE. Images

Crack after new installation on VOLAKAS MARBLE.

Crack after new installation on VOLAKAS MARBLE. Description

We have installed a month ago, Volakas 12 x 12 in a bathroom; walls and (http://maplered.com) floor total size of bathroom L6xW10xH8
Now we have observed two or three Tiles (http://www.g682.net) on the shower walls with a hair line crack. There is no vain behaind it. I
s this normal on this Marble (http://www.lightemprador.com) after installation? 
Please I would like to receive your urgent response?
 
Thanks in advance!
 
Sparclean.