Unallocated inode

[Paul Ripke <stix%stix.id.au@localhost>]

I'm currently running kernel:
NetBSD slave 6.1_STABLE NetBSD 6.1_STABLE (SLAVE) #4: Fri May 23 23:42:30 EST 
2014
stix@slave:/home/netbsd/netbsd-6/obj.amd64/home/netbsd/netbsd-6/src/sys/arch/amd64/compile/SLAVE
 amd64
Built from netbsd-6 branch synced around the build time. Over the
last year, I have seen 2 instances where I've had cleared inodes,
causing obvious errors:

slave:ksh$ sudo find /home -xdev -ls > /dev/null
find: /home/netbsd/cvsroot/pkgsrc/japanese/p5-Jcode/pkg/Attic/PLIST,v: Bad file 
descriptor
find: 
/home/netbsd/cvsroot/pkgsrc/print/texlive-pdftools/patches/Attic/patch-ac,v: 
Bad file descriptor

fsdb tells me they're "unallocated inode"s, which I can easily fix,
but does anyone have any idea what might be causing them? This
appears similar to issues reported previously:
http://mail-index.netbsd.org/tech-kern/2013/10/19/msg015770.html

My filesystem is FFSv2 with wapbl, sitting on a raidframe mirror
over two SATA drives.

Cheers,
-- 
Paul Ripke

"Great minds discuss ideas, average minds discuss events, small minds discuss 
people."
-- Disputed: Often attributed to Eleanor Roosevelt. 1948.