My 0.02 worth. A crush sleeve even directly from Ford is not an $$ item. Don't take a chance on reusing.
If the pinion bearings are correctly pre-loaded, the absolutely should be no in/out play on the flange. Any in/out flange play indicates pre-load is gone.
How did you perform the initial flange install onto the pinion? Did you use the special tool or just use the nut? If you used the nut, consider using an OLD nut to press the flange onto the pinion. Use the NEW nut for the final pre-load measurement.
Have you considered the possibility that the bearing races were not FULLY seated in the housing? This could explain how it is possible to have the correct pre-load on initial crush but then no pre-load later.
Also remember to put some RTV silcone between the pinion nut, pinion shaft, and pinion bearing. This will prevent oil migration between the splines and the pinion nut (Ford TSB).