Uhmmmm....better check out the condition of your allen head wrench set. Thee tip of the wrench might be worn out and too loose (try to avoid using the ball type tips if you don't really have to, as they have less material contact with the socket on the head. I think they can strip the bolt head sockets easier because of this) when inserted into allen head bolts they do wear out after some years of use.....or you might have used a non-metric set on the bolt by mistake(??). If the wrench is OK, it might then be that the bolt manufacturing tolerances are bad and should be returned to Fizik as a defective part for exchange. Striping out allen bolt heads is not that easy unless you have a worn wrench tip or you wear out the bolt head hole from lots of use, you noted that your seatpost is an X-mas gift, so I assume it might be new so this it's kinda unusual for the bolt to strip so easily if you did not put any sort of crazy amounts of torque on it.
Chombi