That's a question for your card issuer.
I had the same question as AMEX charges me after I return the car at the end of the rental. This last rental was with Avis through Priceline and I was charged for the insurance...but I also purchased a tank of gas from Avis apart from the Priceline bid, so AMEX's system had an Avis charge to go by.
At the end of the day you should ask the issuer...and then report back for the rest of us.