[plt-scheme] puzzling code compilation version warning for "mzscheme -M errortrace" in Emacs

After enabling error tracing in Quack in Emacs by setting the default startup option for MzScheme.exe to "mzscheme -M errortrace" in "Quack -> Options -> Default Program," and adding "C:\Program Files\PLT" (the directory containing MzScheme.exe) to both my user and system PATH environmental variables, when I now invoke the 'run-scheme command in Emacs, either by entering "M-x run-scheme", or by typing F5, the following version warning occurs:

--
Welcome to MzScheme v372 [3m], Copyright (c) 2004-2007 PLT Scheme Inc.
> c:\bin\plt\collects\errortrace\compiled\errortrace.zo::0: read (compiled): code compiled for version 371, not 372
--

Apart from this version warning, MzScheme seems to work fine in Emacs.  This version of MzScheme.exe is the one bundled into DrScheme, version 372, english.  Any ideas on fixing this version warning?

Benjamin L. Russell