I have discovered a potential problem...
Yesterday I had the left rear wheel up on jack-stands while I was checking the brake. To do that I put it into "drive" and let the wheel turn a bit and then applyed the brakes until it stopped.

After that I put the car in neutral and went out of the car to have a look, and surprisingly enough the wheel is still turning!
And i couldnt get it to stop with my hands, had to go into the car and apply the brakes in order for it to stop.
Once I let go of the brakes it started spinning again, during all this I had the gear in "N".

I own a pointiac Firebird 3.1 v6 -92, with I think(can it be?) a TH700 transmission, no limited slip. Is this normal or should i be worried?