Received an overdue notice for a parking violation, but never actually got a ticket. How do I appeal?

I received an overdue notice today for what appeared to be a meter unpaid fine from last month in June. However, I never actually got a physical bright orange ticket on my dashboard. I've been parking at the same meters in the area for over 3 months now since I've been heading to the nearby gym and have always paid to 8pm (sometimes over just to get 5 mins to hit 8pm and it only accept quarters!). I've also never received a parking fine before, does that help? How do I appeal this if I never got a physical ticket? Thanks in advance!