Normal
I would like to suggest to you to have the dealer check the block deck, the treads for the head bolts/ studs, the bolts or studs to see if they are stretched, also the main bolts, caps, and block threads. I have dropped a few valves in some older motors and you will be surprised at how much gets messed up from it, some to the point that the whole motor was junk. It is a shame that Ford has not stepped up and replaced your motor.