Got it several times, typically from /proc entries:

error for /proc/4906: lstat /proc/4906: no such file or directory

2 observations:

• This is also in warning class, should not be an error! If file has vanished during the backup, then oh well, there's nothing to backup, it's no error, but can be a warning (just like other cases of fast moving files).
• If the file that has vanished is excluded, this is my case for the example above - I have excluded /proc/*, then I think the most appropriate action is to not even warn, just skip over the error.

That lstat() is done on excluded entries possibly uncovers another bug, maybe exclude filter should be more efficient? Pending further investigation...