Bulb lifetime is an average.
Some bulbs will burn out FAST others will last a LONG time.
It could be one of the bulbs on the FAST end of the bulb lifetime. I have had house light bulb burn out soon after installing so, it happens.
Or if the enlarger is used, the first bulb may have been used for a LONG time before you got it, so it was on the last hour of its life.
Hope the 2nd bulb lasts.