Based on the 2 invoices you had so far there are no charges that I can see for additional minutes. We do record every call you make so they do appear on your bill. However as the below image shows we separate free and included (in your plan) minutes:
Looking closer at my October usage I now understand only 65/100 of my anytime minutes have been used.
However I have used 99 airtime minutes. So yes! No charges for the 34 minutes used during my free time.