I tried to reverse yesterday and the thing just acted like it was in natural (auto gear box). Do you think this is a sign the gear box is on its way out and is it covered under warranty?

I had a leak on my automatic transmission which was dealt with under warranty.

 

I would definitely have the fluid level checked first. If it is giving you no other indications then I would believe it is nothing more than that.

 

Did the fluid level check fix your problem? I noticed on mine this morning a bit of a jolt throughout the car when shifting into reverse on my '05 LTD (94k mi). If changing/adding fluid seems to make that much of a difference, I might consider trying that first before investing in diag and likely a repair. ::crosses fingers::

 

This is an 18 month old post and the OP never bothered to give an update on his 'natural' problems. I had to read the post twice to figure out what he was talking about.

 

@ 94k miles you should have already done your transmission service, which requires a flush and filter replacement.