Error in dosfsck, not fixing usb drive, bug ?

[Richard]

ran the command: sudo dosfsck -vV /dev/sdc1
to check out my external USB drive (vfat),
and it found some errors.. eg:

/2 BK/.Buy & Sell Lists.directory/4sni/cur/1159840134.5568.1b3o0
  Contains a free cluster (2397246). Assuming EOF.
/2 BK/.Buy & Sell Lists.directory/4sni/cur/1159840134.5568.1b3o0
  File size is 3483 bytes, cluster chain length is 0 bytes.
  Truncating file to 0 bytes.
Checking for unused clusters.
Reclaimed 921 unused clusters (15089664 bytes).
Checking free cluster summary.
Free cluster summary wrong (7734511 vs. really 7735433)
1) Correct
2) Don't correct
? 1
Starting verification pass.
Checking for unused clusters.
Leaving file system unchanged.
/dev/sdc1: 83846 files, 2027818/9763251 clusters
rick at KB32bit:~$     
--
I enter in "1" to FIX it, however it not fix, why ?? is this a bug?

Thanks -
Rich