Light bulbs burning out

Question

My microwave has two tubular bulbs for illuminating the range below. One is constantly burning out bulbs (they only last for a day or two). I checked the specs, which call for a 40-watt bulb, and that's what I am using.Any ideas?The other bulb (the left one) seems to be fine.P.S. I did not disconnect the power before changing the bulb, but the lights were in the off position.