I assume this issue has been reported to the Type Certificate holder ATR. It seems strange that if this aircraft has not suffered any unusual event to cause this why there is not an AD or mandatory SB to inspect the other aircraft in service?
I have seen an AD relating to a previous issue of cracking around the cockpit windows.
The cracking could be related to errors made in production such as scribed markings or failing to deburr holes and edges. The DH comet problems were related to this and the square windows causing stress cracking.
For anyone interested in the detail of the certification this is the TC.
http://easa.europa.eu/system/files/d...3-17102012.pdf