Great! Thanks for checking into this further. Based on the sample code you found, it appears that the page mapping problem I am experiencing is consistent across these GLCDs. While your hypothesis about the possible cause, is better than anything I could proffer, per page 12 of the datasheet, the page address defaults to page 0 on reset, not page 4. If this problem could be corrected by sending the appropriate reset sequence, Adafruit's sample library would include such an initialization routine, versus, containing a routine to remap the pages. Now that I know that the problem is hardware, I can deal with the issue by assigning the correct page address to page variables, versus, using the page address commands discussed on page 16 of the datasheet.
Surely, I am not the only person who has or will buy one of these displays from Adafruit and will rely on the datasheet for technical information regarding its use, versus relying on sample code. I suggest that Adafruit make future buyers aware of this "Feature" and of the possible work around. Not only will this prevent others from spending needless time trying to figure out why their code does not produce the expected results, it will allow them to make an informed purchase decision. Had I known this in advance, I would not have purchased this GLCD. For $3.00 more, I purchased a GLCD from another vendor that worked flawlessly.
I sincerely appreciate your efforts to assist me with this problem. Great technical service and excellent follow through.