Windows Service stops updating event log

I've got a small project that involves a windows service.  The service is still in the development stages so I'm using the Application event log to keep track of what it's doing.  There's a lot of messages that get sent to the log right now (and yes, I know there's better ways to log but for this work, the EventLog is quick and easy).

At some point however, my messages just stopped.  The service was still running yet I wasn't getting any messages.  I was puzzled as to what could be wrong.  I checked the properties of the Application log to make sure the log size was big enough.  It was set at 512 KB which I thought was big enough, but the setting for what to do when the log size is reached was still set at "Overwrite events older than 7 days":

I had been doing so much logging, I had filled up the log, but none of the entries were over 7 days old -- so the calls to add log entries were just being ignored.  I changed the log settings to "Overwrite as needed" and I stopped losing log entries.  Now I know I'm not going crazy!