Completely normal.
The way it has been explained to me in the past is that that sound can be from 2 different sources: The VVT cam phasers or the transmission.
The cam phasers have a little pin to limit the amount of movement. When it's cold, the oil has drained and it gets loose upon start-up, slapping back and forth until oil gets there.
The transmission has a small reservoir with a small hole in it that allows it to drain when the engine is off. Upon start-up, it makes the sound until it fills with trans fluid.
Of the two, I tend to believe the cam phaser. My 3.6L makes more noise for longer, which is kinda odd since it was replaced only 55K miles ago (at 94K), but the trans has all 149K miles on it that are on the odo.
So, you decide, but it's normal.