mod_deflate not compressing css or js files which have parameters

Can anyone give me any idea why this directive works great for a wordpress 3.1.2 installation but fails to compress any files that have parameters on two wordpress 3.2.1 installs on the same server as the 3.1.2?

WordPress 3.1.2: both jquery.js and jquery.js?1.4 compress
Wordpress 3.2.1: jquery.js compresses but jquery.js?1.4 doesn’t

# BEGIN server side gzip compression of served pages
<IfModule mod_deflate.c>
  <FilesMatch "\.(js|css)$">
  SetOutputFilter DEFLATE
  </FilesMatch>
</IfModule>
#END Gzip compression

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Thanks!