Yes, I have had random issues with this. It seems to crop up when something goes wrong with sync or compact. I have closed the file and compacted by scrolling to file and selecting it. Closed FTM and reopened. This often clears it for me.
Other things I have tried:
Opening another file to break whatever connection is established with the offending file.
Cleaned up hard drive by running disk cleanup to get rid of left over file that might be hanging around.
Some combination of all these :o)