Installed were 12-6" IC rated recessed lights, one light is blowing bulbs frequently
I have not seen this what could it be.
Thank you

Does this one unit have more insulation or enclosure more than the others? Excess heat could be the problem.

-Is there a room above the fixture? Vibration from walking, or jumping children can shorten the life of a light bulb.
-Larger than specified light bulbs can lead to overheating--yet the fixture should shut down before the bulb blows
-A loose socket could be the problem
-Did you use the same bulb for all 12 fixtures? Cheap bulbs will go dead prematurely.

I'm sure it's not a spike in voltage--seeing that the other's aren't effected. I would start by checking the above first, then go from there.

Check the center contact point in the bulb socket to make sure it is making good contact with the bulb( you can even pull them down abit with the power turned off course). Also sometimes it feels like you have the bulb in correctly but in actuality it's not and there is some arcing at the center electrode on the bulb which stresses the filiment on power-up.