If you're talking about doing that next to a NFC transmitter, that's common. Maybe normal. I didn't think a double click would open wallet.
I've had hit & miss success with Apple Pay at stores. Some stores I can just hold the phone near the NFC transmitter and my finger on the home button & it'll go through. In other stores I have to manually launch the Wallet App then hold the phone near the NFC reader. So it's hardly an effortless reliable experience. Add to that wet fingers from picking up cold items with condensation on them & placing them on the conveyor- then trying to authorize with TouchID -which won't work with wet fingers----- that often I just use a credit card instead. Much more reliable & easier.