Odd! I had the same issue, only a lot sooner than you. Dealer replaced R-side cam phaser on my '09 4.6 at 600 miles. Shop did a good job (apparently, altho they had the truck 6 days) with no recurrence of the noise and no quality issues--oil leaks, etc.--so far at 2800 miles.
I only hope this isn't going to be a recurring theme every 10-15K miles. Wierd thing is that this isn't new technology for the engine. VVT has been used in the 4.6 (in other Ford vehicles) for several years now.