Combined CSS Query Strings

I use W3TC to combine and minify the CSS files for my site. We recently changed a CSS file, and minify.php rebuilt its results but didn’t change the ?file parameter, and so browsers had the old version cached and wouldn’t update. We have “Prevent caching of objects after settings change ” checked, but it won’t append a query string to files that already have them, as in the case of the combined CSS file.

Is there a way to have the combined CSS file update after a change?

In the meantime, I have w3tc’s minify option disabled, passing that burden off to Cloudflare instead, which achieves the behavior we want without combining. Still, we’d prefer to be able to combine the CSS files if possible.

Advice?

http://wordpress.org/extend/plugins/w3-total-cache/