I am having some troube out of an AFCI installed on a house I recently finished. I know they nuicense trip sometimes but what would I look for to cause it to trip. It may go for days without tripping and then just trip for no apparent reason. The fire alarms, bedroom light w/fan and 1 outside light right outside the door are on this AFI.

Is there a reason that the inspector told me you can only install 15 amp AFI's for the bedrooms or was this just his preference. I pulled the 20's out and replaced them with 15's but I cannot find in the code book anywhere that prohibits 20 amp AFCI's in bedrooms. They make'em and sell'em everyday!
Thanks!