Got an 05 OR, just less than a month old.

When I start the engine and put it in drive, I drive for about 30-40ft and hear a light "clank" sound from underneath.

It only happens ONCE as it starts to go from first to second gear... it won't happen again for the rest of the trip.

But if I shut off the engine and let it sit for a couple minutes (like a run to the store) it will "clank" again when I first start driving again.

It happens every time I drive it, but only once during the trip - at the very beginning.

Is that normal and any ideas what it is?