I've never seen a bulb flash blue, it appears bright red to me as it dies. I did some quick research and was unable to find anything on a blue flash.
It makes a great deal more sense to me that you may be seeing blue in relation to other objects you're looking at, or as your eyes adjust to the blown bulb. Seeing "red" makes sense when you consider how incandescent light bulbs works.
Incandescent light bulbs have a fliament inside them made of tungsten. As the bulb is used, the tungten atoms evaporate (due to heat) and the filiment shrinks. The atoms eventually darken the bulb. By then the bulb has a low "life expectancy."
An incandescent bulb's filament is really hot: Nearly 1/2 the temperature of the sun (2500 C vs. 6000 C.). The bulb produces light by the electrical current exciting the tungsten atoms and turning it into thermal energy a portion of which is emmited as visible light.
Of course, the sun is much hotter and produces different and more types of specturms of light. An incandescent bulb emits visible light in the orange/red spectrum and hardly any in the blue spectrum. (Put more accurately, light is emitted from an incandecesnt bulb in wavelenghts ranging from infared to blue/green but the greatest amount produced is in the red spectrum and just a tiny amount in the blue).
I have no explanation why you would see a flash of blue. Has anyone else experienced a blue flash from an incandescent bulb?
Oh yeah, turning an incandescent bulb on and off doesn't shorten the life of its filament as much as leaving it on does. It's therefore more economical to turn it off whenever possible. The filiment of a fluorescent bulb however are significantly degraded by turning it off and on. I wouldn't turn off a florescent bulb if you're going to turn it on again in a few minutes.
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