2004 Honda Odyssey with stuck transmission! Help!

I have a 2004 Honda Odyssey with 36,000 miles on it. The vehicle
currently drives and shifts fine. The only problem is the gear
selection lever will not move past D. In other words I can only put
it in D. Not D3, 2, or 1. I am aware of the safety recall and the
inspection of 2nd gear, that was taken care of. All other maintenance
including the 30,000 mile has been done at the dealer. The vehicle is
still under warranty so I will be calling the dealer tomorrow, but I
was just wondering if anyone else has had similar problems? What
might cause this and what the solution is? Any info would be great!!!

Also, the tranny fluid was changed at the 30,000 mile mark. And with
only 6,000 miles on it now, it seems very brown and burnt suggesting
excessive heat. Any thoughts on this???

Thank you.