check_disk reports wrong inode usage

Description: Ubuntu 12.04.4 LTS
Release: 12.04

dpkg -l |grep nagios-plugins
>
ii nagios-plugins 1.4.15-5ubuntu3.2 Plugins for nagios compatible monitoring systems (metapackage)
ii nagios-plugins-basic 1.4.15-5ubuntu3.2 Plugins for nagios compatible monitoring systems
ii nagios-plugins-standard 1.4.15-5ubuntu3.2 Plugins for nagios compatible monitoring systems

Our nagios check_disk check reports 99% use of inode, but thats wrong

kinda looks like this nagios_plugin bug (http://sourceforge.net/p/nagiosplug/bugs/541/)

for example:
/usr/lib/nagios/plugins/check_disk -w 10% -c 5% -W 5% -x /backup_vms -x /media/BACKUP_QUARTERLY -A -i '.gvfs'

reports:
DISK WARNING - free space: / 11806 MB (26% inode=88%); /dev 12043 MB (99% inode=99%); /run 4814 MB (99% inode=99%); /run/lock 4 MB (99% inode=99%); /run/shm 12054 MB (99% inode=99%); /home 237213 MB (69% inode=99%); /data 859590 MB (43% inode=98%); /backup 487962 MB (9% inode=99%);| /=33118MB;42578;44943;0;47309 /dev=0MB;10838;11440;0;12043 /run=7MB;4338;4579;0;4821 /run/lock=0MB;4;4;0;5 /run/shm=0MB;10848;11451;0;12054 /home=105345MB;324665;342702;0;360739 /data=1116179MB;1872564;1976595;0;2080627 /backup=4857316MB;5068223;5349791;0;5631359

/usr/lib/nagios/plugins/check_disk -w 10% -c 5% -W 5% -p /backup

reports:
DISK WARNING - free space: /backup 487962 MB (9% inode=99%);| /backup=4857316MB;5068223;5349791;0;5631359

/usr/lib/nagios/plugins/check_disk -w 10% -c 5% -W 5% -p /home/

reports:
DISK OK - free space: /home 237213 MB (69% inode=99%);| /home=105345MB;324665;342702;0;360739

`df -hi` output:

Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/sda3 3.0M 334K 2.6M 12% /
udev 3.0M 575 3.0M 1% /dev
(...)
/dev/sdd1 350M 1.9M 348M 1% /backup

Disk check should be OK (and inode should show ~ the same results as df -hi)