I'm pretty sure this change was a result of the server move last weekend. Not only did we upgrade to the latest version of vBulletin, but we are also running Red Hat Enterprise Linux. We were running under Red Hat 7 on the former server.
Joerg, who is our server admin, is away until Monday, but I'll let him know about this. Maybe there's a configuration setting that needs to be changed.
But it may also have something to do with the way the data was loaded to vBulletin on the new server. I recall Joerg mentioning that he "imported" the data.