backup.tib files are sometimes not deleted on the hard drive

Hi,
I sometimes have a strange behavior since using windows 8:

I went into my backup folder to delete a old *.tib backup file. I used windows explorer for deleting the file.
There was no issue until here and I directly deleted the file without going through recycle bin first. Then I booted up my Acronis True Image 2013 boot cd and wanted to create a new backup. I switched to the backup folder and the backup file I did delete before was visible in my backup folder again!?

Without creating a new backup I booted up windows and checked the backup folder again, and even windows explorer did show up the file again. So I tried to delete the file in windows explorer the same way again, and after that it got finally remove the file.

This is the 2nd time I have this behavior on my machine. Any ideas what could cause this strange behavior?

Thanks