huge tree of package descriptions in /var/tmp

[andrew@pimlott.ne.mediaone.net (Andrew Pimlott)]

I fear this question will have an embarassing answer, but I just
found a large file tree in /var/tmp/filexQ70qA on my Debian Woody
system.  The contents seem to be some form of the Debian packages
database.  filexQ70qA/ contains a huge number of directiories (~
5000--BTW, that takes a while to list in ext2 ;) ), each named after
a Debian package.  Each of those directories contains a single file
of the same name, whose contents is the packages entry for that
package (eg, libapache-request-perl/libapache-request-perl contains
"Package: libapache-request-perl\n...").  The whole tree takes up
about 50 megs.

Is there any known program that creates such a tree?  Or, is there
some archive that unpacks to this structure?  I can't imagine that
any standard Debian tool does this.  The dates (mtimes and ctimes)
are all from back in March.  However, my system recently went from
~60 Mb free on the disk down to 0 (which is the reason I started
looking for disk hogs and found this anomaly), so I'm slightly
suspicious.  Needless to say, I don't remember creating the tree
myself.

Can anyone put my mind at rest by suggesting how this came to be?
A direct email Cc: would be appreciated.

Thanks,
Andrew