Identify the cause of increased thread queue size

I have a simple app which queries an address for data. It ends up having items queued on the thread queue (5+) and I am wondering how to debug it. This happens very infrequently maybe once a week and enabling logging has not helped. As of writing this post, the queue size is 5 (Last Active=2020-12-06T12:05:26-06:00). Once this happens, I have to restart AppDaemon completely. I feel I am missing something very obvious.

class Updater(hass.Hass):
    def initialize(self):
        ...
        self.fetchData()

    def terminate(self):
        if self.callback:
            self.cancel_timer(self.callback)
            self.callback = None

    def fetchData(self, kwargs=None):
        self.callback = None
        try:
            data = requests.get(self.url).text
			...            

        except () as error:
            self.log(f"Error connecting to {self.garage_address}.")
        finally:
            self.callback = self.run_in(self.fetchData, FETCH_INTERVAL)