Your lightbulb didn't die, Zim. This actually happens quite often when there is a power surge. The electrical system within your refrigerator reversed polarity, causing the motor to spin in the opposite direction and the lightbulb to turn on when the door is closed, and turn off when the door is open. This won't do any damage to the refrigerator, but the increased exposure to incandescent light may affect the taste of your beer. It's best to have a properly trained electrician take a look at the appliance to see whether it can be fixed.
Before calling the electrician, though, make sure that this is the problem (you don't want to call him for nothing, now do you?) Get inside the fridge and close the door. Remember to take the beer out first.