Why should I tell DFAS my Temporary Disability Retired List is Over?

MAJ Ken Landgren great question, I would call DFAS
http://www.dfas.mil/customerservice.html
Found some info that might be useable:
During and After TDRL
When on TDRL, it is as though the service member is medically retired from the military. He does not perform any military duties, is given a temporary Military Disability Rating of at least 50%, and receives full Military Disability Benefits from the DoD and the VA.
During the TDRL period, the service member must be occasionally re-evaluated (generally every 18 months) to determine the progress of his condition and his disability ratings updated to reflect any changes in his condition.
If the condition improves enough during his time on TDRL, the PEB may find the condition no longer unfitting. In that case, the service member can choose to either return to full active duty or permanently retire from the military. If he chooses to return to full duty, all DoD disability benefits he was receiving during TDRL will stop.
If the service member chooses to permanently retire or if the condition worsens, or at least does not improve, and becomes relatively stable, the PEB will medically retire or medically separate the service member with a permanent Military Disability Rating based on the severity of his condition at that time.
All TDRL cases will receive a permanent rating based only on the VASRD criteria that is in effect at the end of the TDRL period.

This is too good to be true.

MAJ Ken Landgren I hope its in your favor!

With the battles against me, it's hard to believe good things will happen lol.