Scott,
I have run into it also. Sometimes after you have filled out values under the configuration specific tab and then later go back to edit them a property called "Intermediate" will be listed where Description or Date etc. would be listed. I believe it only ever shows up in the configuration specific tab, never in the "Custom" tab. As everyone above says you can either leave or delete it. Can't say for sure but I believe I have seen it since upgrading to SW2004 SP3.
mncad