Clear BehaviorSubject of queued events as each is addressed in Angular2 with Observables

I'm having a problem that I'm sure is entirely based on my (lack of) a complete understanding of Observables.

This is an Angular2 (v4.0.3) project using rx/js and Observables.

I have a state store that holds events in a state service:

  // Observable string sources
  private currentEventStore = new BehaviorSubject<string>("");

  // Observable string streams
  public currentEvent$ = this.currentEventStore.asObservable();

  // Service message commands
  setCurrentEvent(nextEvent: string) {
    this.currentEventStore.next(nextEvent);
  }

I subscribe to currentEvent$ in my components to listen for events, and then act on them.

this.stateSvc.currentEvent$
  .subscribe(
  currentEvent => {
    this.currentEvent = currentEvent;
    if (currentEvent != '') {
      this.handleCurrentEvent(currentEvent);
    }
  });

The problem I'm having is that the store is accumulating all events and returning all of them each time, so that when I spawn a 'create' event, my subscribed function picks up the event and creates a record - perfect on the first pass, but if I spawn a second 'create' event, my subscribed function picks up 2 events, and creates 2 records, and on the next 'create' event it creates 3 records, and so on.

What I need to happen is for the event to be flushed out of the stream so that the currentEvent$ store only holds events that haven't been addressed.

Is there a way to flush the store? Or is there something I'm missing here in my expectations and implementation?