My approach would look like that:

use File::Find::Rule;

my @files = File::Find::Rule->file
                            ->in('/mnt')
                            ->name( qr(\d+\.$host\.mksysb) )
                            ->maxdepth(1)
                            ->mtime(">= $mksysb_cutoff");
[download]

Actually I already have a script running that pretty much works like that and it works well.

Cheers, Flo