In our testing environment http://env1.rice.kuali.org/portal.do, KNS Kitchen Sink the fieldsets have borders around them. You can see this on the first page with the checkbox/radio groups and the Lookup page (see screenshot). However, none of the developers see the borders in test. So we think it might be due to use of the minified CSS.
One thing to note, fieldsets have a border by default, but it should get turned off by fss-reset-global.css. Possibly ordering in the minified version is causing the override to not happen.