Repeet trying to load calendar from item ID

I installed repeat awhile back and never had any problems with it. Recently, however, the site that is running it has gotten item ids that are in the thousands. so a url will end with something like: index.php?/stories/item/1246

repeet seems to be trying to display a sidebar calendar starting in the year 1246 (which makes it default to december 1969 apparently). I tested this hypothesis by looking at the page: index.php?/stories/item/124 which has no problems. What’s the deal?