Here is Roland's response to my question:
"Stretch Tuning" is the default tuning for most Roland digital piano and keyboard products. Roland applies this setting to our products because stretch tuning is the accepted tuning method used to tune acoustic pianos.
Some of our products have the option of adjusting the amount of stretch tuning or turning stretch tuning off. Other Roland products, including the FP-4, do not have those options. These options, or lack of options, are per the specifications of each individual product."

I can grasp the concept of making the upper notes SLIGHTLY different from the lower ones (harmonics and all) but it seems Roland has 'stretched' this concept to the point that the notes sound 'out of tune'.... Unfortunately I own the FP-4, and have to live with their lack of 'options'...

Thanks....