Yes Jim , do all that ,, run it up to temp, or after a long run, keep the engine idling while testing the fluid content,
so i suppose its OK.
When they replace the rear seal (again) next tuesday, I will check again, regards john

Temp marks , at the bottom of stick there two markers , i was told the lower one is when tranny is cool/cold, the upper one is when at operating temperature, I have been checking at operating temp