I also have this noise on my brand new 2013 Focus. A guy posted a YouTube video which really illustrates what it sounds like and how long it lasts. This link is:
The dealer never heard of it before I brought it up. Their research came up with a notification from Ford which read:
"SSM 12013 - 2013 Focus - Clicking noise from the automatic transmission after vehicle is unlocked and prior to engine starting.
2013 Focus Vehicles equipped with the Powershift DPS6 transmission may experience a clicking noise from the transmission after the doors are unlocked, opened and prior to the engine starting for up to 3 minutes. The noise is the transmission shift motors waking up and preparing for startup. Attempts to eliminate the noise should not be made."
I am very, very unhappy with Ford's response to this ridiculous response. I intend to pursue this issue to Ford in Michigan, local TV media and Washington, D.C. for a recall notice from the feds.