I have created a 350GB encrypted (aes128) sparse bundle disk image within a 360GB partition (mac os extended journaled), and copied files there until it got almost full. The Finder showed 4GB of available space within the sparse disk image.

Then I deleted (rm -rf) all the files within the sparse disk, but the Finder still shows 4GB of available space! I am aware that the sparse bundle disks do not automatically shrink, but how come the space within the sparse bundle does not increase? It's definitely not a Finder bug since the 'df' output is the same as Finder's. By the way, I am running mac os x 10.5.8. If I try filling up the disk again, it works fine, even though the Finder still shows 4GB.

Did anyone experience this problem before and any ideas on how to fix it? I am also worried about the potential impact it may have on my Time Machine backups I have created this disk for.