I've also used it, and I think there's a better way than the one you mention Markie. Before you reach the gateline open up your Passbook, tap the card you want to use; once you've done that the screen will read "'XYZ Card' is ready for Apple Pay". Put your thumb on the scanner, and after a second or two you should see that text disappear and be replaced with text that reads "Hold Near Reader to Pay". Once you've done this, your phone will basically act like any contactless card for one minute, you won't need to reauthenticate with your finger while you're on the gateline—now you can approach the gate and place the top of your phone on the reader like it was a contactless credit card and you're through. This should eliminate the sometimes-it-works-sometimes-not issue that you have when waiting for Apple Pay to pop up on its own.