There's no sync there, here's what the output for my Kindle shows
Code:
/dev/sdh1 on /media/Kindle type vfat (rw,noexec,nosuid,nodev,sync,uhelper=udisks,uid=1000,gid=1000,shortname=mixed,dmask=0077,utf8=1,showexec,uid=1000,gid=1000)
Note the word sync.
While I doubt this is the cause of your problem (since if you eject properly, the filesystem should automatically be flushed), it is good practice to mount removable devices in sync mode, this protects them from corruption in the case where someone yanks the cord, instead of ejecting properly.