Also in the good old days if you sealed the wrong number you had some time to just hang up without harm done. Today the connection is made the moment you pressed the button or in this case when Siri decided to call.

Happened to me too while being in the car. With every message written by Siri it feels like you need to confirm 2 or 3 times (I think it is only once but again) but it calls happily people from your phone book.