Yes IME when this happens and you're signed in, you can then find the record on hold in your profile. You can usually cancel that online if needed and then it's a couple of minutes at most for the seat to be available again. Or sometimes the connection messed up during payment and you can try to pay again like any other hold. I'm pretty sure this fuels some of the "the airline saw me look at the flight and then raised the price!" conspiracies.