ext3 partition -- deleting file doesn't reclaim disk space

I have a linode64, running Gentoo. I recently transferred a large file to the system….it was a little over a gig.

Today I deleted the file, but found this:

host tmp # df -m
Filesystem           1M-blocks      Used Available Use% Mounted on
/dev/ubd/0                2728      1762       939  66% /
none                        30         0        30   0% /dev/shm

Previously, there was just under 2 gigs free…

I've had this issue before with a few linux systems, and always had to re-mount the partition in order to reclaim the space. Is there any of doing this without having to re-mount the partition, which in my case, means rebooting the machine?

Thanks!