You may also want to check to see if there is moisture inside the housing, along with piece of shattered bulb. If your bulb comes out in one piece, then I would say it was just normal end of life. If it comes out with the glass missing, then you should unbolt the lamp from the mount and look inside for water and the rest of the bulb. The stock foglamps on my 97 leaked pretty badly, enough that the housing was half full of water. That was remedied by cleaning the inside then sealing visible cracks with gray RTV