Warning on Flush of a Preset

Hi, I try to flush a preset, but an error occurred.

warning: rmdir([...]\files\imagecache\team_minifoto) [function.rmdir]: Directory not empty in [..,]\modules\imagecache\imagecache.module on line 695.

After that I check the drectory's contents and I found that it's empty.
The error is that the $d directory object is never closed, and removing it while still open raise that error. I solved adding (in a clean way) the next lines:

$d->close();

before the call to rmdir() resulting in having this code:

$d->close();
rmdir($path);

I'm using latest 6.x version avaiable.
Regards