Suggest then to try Repairing your Gmail Contacts and see if that fixes the contacts sync error. That should re-sync it up with your Google Contacts online.
Failing i would next suggest if you use Gmail as a normal IMAP account, to remove and re-add your Gmail account via the “Automatic email wizard” via “Menu / Accounts” and see if that fixes it.
Note:- If you do remove and re-add the account, backup first via “Menu / Backup”. You can see when the backup is complete in “Show Operations” via the dropdown on the right of refresh top left