Is there a V-TOLL charge showing? That’s the indication they use if the transponder can’t be read but they match your license plate number (which is different from roll by plate because you have an account, but the transponder didn’t read, and is charged a penalty).

They set the rates, it’s not like some third party has to update the website six months later, and I’ve always seen it be accurate so I figure there’s something else. Is there a chance you put the wrong entry or exit point — some of them are confusing in the web page. V-TOLL seems most likely to me although I don’t remember the rate for that off hand.

They’re generally helpful and friendly, you could give them a call after the holiday and talk to someone even if it’s just to get clarification about what happened so you can prevent it in the future.