Error in latest values for disk free space

[ays]

Hello everybody !
I have strange problem with 1.1b7
I have a Solaris host, and I monitor partition /usr5/

key is

vfs.fs.size[/usr5,free]

and multipler is custom 1024.

I also have a trigger

{front-2:vfs.fs.size[/usr5,free].last(0)}<5G

Now df -k shows that there are 5183208 free kylobytes.

Trigger is ON, which is pretty OK (5183208/1024/1024=4.94Gb)

But for some strange reason, latest value is 5.31 Gb ?

After checking other hosts I must state, that all the 'last values' are greater then in real life, but triggers works really nice.

Could somebody confirm such bihaviour ? Is it a bug ?

[ays]

After migration to 1.1b8 this problem is still exists.

Please, confirm this behaviour, or point me to my misconfiguration