Weird DataGridView Behavior

I can't understand why this happens. I have a page level variable that stores an object I call EventCollection. That object contains a List<> of things. I use the code below to bind the list to a DataGridView.

this.dataGridViewEvents.DataSource = null;
if (this.EventCollection.List.Count > 0)
{
    // Don't assign an empty List<> to a DataGridView DataSource. It causes weirdness when selecting rows if they're added later.
    this.dataGridViewEvents.DataSource = this.EventCollection.List;
}

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Later on if I want to add a new item I simply do this:

SierraEvent newEvent = new SierraEvent(this.ParentId);
this.EventCollection.Add(newEvent);

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Then I rebind the datasource to the DataGridView control. This works fine as long as I make sure not to assign an empty list as the datasource. If I do that then I get a very odd behavior. After adding items to an empty list, if I then select a row in the DataGridView I get the following Exception:

System.IndexOutOfRangeException occurred
  _HResult=-2146233080
  _message=Index -1 does not have a value.
  HResult=-2146233080
  IsTransient=false
  Message=Index -1 does not have a value.
  Source=System.Windows.Forms
  StackTrace:
       at System.Windows.Forms.CurrencyManager.get_Item(Int32 index)
  InnerException: 

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I've managed to avoid the problem using the above logic but I am at a loss to understand why this happens in the first place. Is this a bug in the DataGridView control?