New Construction home and recessed light bulbs keep blowing out??? HELP?

I have a new construction home that i am building. Everything is wired, but there is 2-3 bulbs that continuously blow out... I have had to change them twice already in 1-2 weeks. They are the correct Par20 bulbs for the 4" juno cans and I also have an extender on them so I know the bulbs are not getting hot. What else could be blowing these out so quickly ??