[plt-scheme] mzscheme is still looking for a deleted collection

I have PLT 208 installed on a gentoo box.  I had a copy of Schematics
SRFI 13 installed in my private collections, but it seemed to be
interfering with another collection, so I deleted it, but I left the
rest of the SRFI tree there (I need Schematics' SRFI 19).  However,
the module resolver seems to insist on looking for SRFI 13 in my
private collection path; it's as if it descends into the SRFI
directory, sees that 13.ss is missing, and gives up, instead of
continuing down the collecion paths:

Welcome to MzScheme version 208, Copyright (c) 2004 PLT Scheme, Inc.
> (require (lib "13.ss" "srfi"))
default-load-handler: cannot open input file:
"/home/gweakliem/.plt-scheme/208/collects/srfi/13.ss" (No such file or
directory; errno=2)
> (current-library-collection-paths)
("/home/gweakliem/.plt-scheme/208/collects" "/usr/share/drscheme/collects")

Is this a bug, or WAD?  
--
Gordon Weakliem
http://www.eighty-twenty.net/blog