[SomeGeoffGuy]

That sounds like a bent shift fork to me. It's fairly common when people put aftermarket shifter on the car without the correct stops to prevent this exact thing, but can happen if something is misaligned or out of spec from the factory too. Basically if you hit third gear too hard, the fork bends. I had the exact same thing happen to me on a 2002 Firehawk when I put a B&M shifter in it. My buddy drove it one time, and I told him not to do it, but he powershifted it anyways and bent the fork.

I had it quoted at a trans place and they told me the fix was basically to replace the 3-4 gear assembly as a unit. At least you are under warranty!

-Geoff