It's fairly common on King Airs, the windshields de-laminate if they get cold soaked and then the windshield heat is turned on. After they de-laminate then they stand a bigger chance of shattering.
Look for signs of de-lamination in the corners.
Then I know a guy who had a B200 that was breaking windshields like crazy and they found that the frame was tweaked slightly and was causing the problems.