Hi George,
The link you provided doesn’t seem to function any more, so I can’t check your site for myself, but my guess would be that what you were experiencing was simply the default behaviour of the calendar widget.
By design, it shows upcoming events in the current month by default. If, as an example, you have 5 events coming up later in June then – at time of writing – you would probably see all 5 listed below the widget by default.
As time moves along though, some of those events would drop off the list: on June 15, for instance, you’d only see those events taking place on or after that date.
Might that explain this?