Bobc
I have a 7040 which is likely quite similar.
The 4 wd lever does not immediately pull the fwd out of engagement.
As I continue to drive and turn the light will suddenly go off.
The front and rear axles do not run at exactly the same speed and you can build up some twist in the system which tends to hold it in gear.
Hard surface operation does not allow much slippage and tends to prolong the release.
Backing up and turning will sometime release it. I have not tried this but likely lifting the front end with the loader and with the front wheels in the air back up.
The more I watch the light the longer it tends to stay on
Dave M7040