Got double glazed units installed two weeks ago. Bay window has safety glass with seperate stained glass panes above. Work finished late on Wednesday, following morning at 5 am we left on a weeks holiday in Spain. After return neighbour told us that on the Thursday morning he noticed cracked stained glass unit (crack from bottom right to top left). Glazier implies that something was thrown at the window. From inside you cannot really see the crack. Could that pane of glass been faulty?