Oracle Portal Virtual Host and SSL

I recently ran into an issue that Oracle Portal was presenting the wrong base href in some pages. This was a virtual hosted environment, that is, several machine names point to the same installation of portal. We had followed the virtual hosting documentation perfectly, and in fact, we had it running for quite some time without any issue. The issue cropped up when we added an additional virtual host.
This additional host was the first one that was not SSL. It took a little while to figure it out, but the solution was to make sure that all of the https (ssl) virtual hosts appear in the httpd.conf file prior to the first http virtual host. I'm still not sure why this would make a difference, but it solved the problem.