I have a 2009 TL with 36k on it and just out of warranty. The doesnt happen all the time but I seem to notice it more when the car is cold and not warmed up. This is the exact replication of the issue. I put the car in reverse, back out, now put it into drive, I drive about a foot and hear a clunk noise underneath in the front like something just engage. Everything shifts and works fine though.
I can put it in reverse, back up a few feet, put it into Drive and I will hear it again once I start to move forward. any thoughts or advise?

 

its normal....