iCal stopped deleting old events

Hello,

I updated to Mountain Lion a while ago (back when it was first released) and noticed a few weeks in that iCal stopped deleting my older events. I used to have the preferences set so that iCal would delete events older than one week, but now I have every event in my calendars since updating to Mountain Lion. I'd prefer not to go through and manually delete every event... does anyone know what happened to that preference? I can't seem to find it in my settings anywhere, nor in my iPhone's calendar settings.

Thanks!