Mine

2009 V6, crew cab, long bed, 4x4 SE auto (total miles, 2600.) Bought the end of May.

OK, I too have this problem. It seems to be intermittent as I tried today to duplicate, but couldn’t. It seems that sometimes when stopping for a traffic light, when you hit the gas the trans. acts like it was not in gear and suddenly engages which causes the drive shaft to clunk. I had my wife shift from reverse to drive ( while parked) and I looked at the drive line. When going from reverse to drive the drive line took about 3 to 5 seconds before it showed any movement. It acts like the trans is not staying engaged, (no constant pressure on rear end while stopped) so when you hit the gas, even gently, it suddenly engages and I am sure will be hard on the u-joints.

Any ideas..?

I am going to bring this up when I go in for my first oil change.  Maybe you have seen this before?