I had something similar happen in SFO last year- authorization showed up on my Apple Watch as a credit card charge notification as my husband was pulling out of the parking ramp there but when we went to turn in the car at the end of the trip, Hertz had cancelled the rental shortly after we left.

The non-rental was caught when we turned the car in at the end of the trip and we paid at that point. Got like a $50 discount because it was a 20+ minute wait to talk to a CS rep. Fortunately, we had planned to get to the airport fairly early for the trip home.