missing disk space - pfblocker and pfsense 2.5.0

vajonam

with pfsense 2.5.0 and pfblocker running. there is some ghost disk space somewhere ! I am not sure what is taking it up.

    $df -m /
    Filesystem                                      1M-blocks Used Avail Capacity  Mounted on
    /dev/gptid/6f34ba9a-3faa-11ea-bfde-40623108486d     13683 3328  9260    26%    /

This shows 3328 megs used

and when running DU. this shows differences!

    $cd / && du -ma | sort -nr | head -n 20
    
    2124	.
    1227	./usr
    851	./usr/local
    605	./var
    512	./var/unbound
    474	./var/unbound/usr/local
    474	./var/unbound/usr
    316	./var/unbound/usr/local/lib
    316	./usr/local/lib
    298	./usr/lib
    249	./usr/local/share
    207	./boot
    132	./boot/kernel.old
    130	./var/unbound/usr/local/lib/python3.7
    130	./usr/local/lib/python3.7
    115	./var/unbound/usr/local/bin
    115	./usr/local/bin
    113	./usr/lib/debug
    102	./usr/local/sbin
    82	./var/db

As you can see du reports 2124 megs used and df reports 3328. What is using this up? this slowly fills up and I need to reboot my router to clear it up! Not sure I have let it get to 100%, but what is the real usage?