It's because I just hadn't got around to adding it yet
As you may or may not know, the events calendar is not automatically populated and as such, is only updated perdiodically. Last time I checked the BC events, yours hadn't been published... however it's now showing on the calendar.
Please keep in mind that nobody should be using the calendar as their sole source of local events. As always, make sure you check the main source (www.geocaching.com).