Canonical URLs not aggressive enough

Recently, I changed my permalink structure from the standard numeric (/journal/archives/337) to a custom setting of ‘/archives/%post_id%/%postname%.html’ (/journal/archives/337/the-post-title.html). This was mostly for SEO and to allow static pages to be created easily if needed.

All existing URLs in the old format (just the post ID) still work fine, which is good, but shouldn’t the canonical URLs feature do an HTTP 301 redirect to my new permalink structure? If not, I can write a little code and a mod_rewrite rule to convert old incoming links, but it seems like the work has already been done and this is built in.

Thoughts?