It doesn't matter what your W-2 shows - there is no filing requirement for an FSA. That is, whatever you see in box 14 (I assume that your FSA entry is in box 14) won't affect your tax return.
Box 14 entries are informational and are designed for your employer to tell you something.
The amount that you agreed to contribute reduces your Wages in box 1 on the W-2. Any amount not spent is generally lost at the end of the year.
But since this does not affect your return, just keep good records. It is unlikely that anyone will ever notice.