Many thanks for the reply.

What you describe is exactly what happened to me. Initial delay posted was 10 minutes, then after I paid the fare difference delay was increased to 30.

I love WN, but my pet peeve is their automated flight status system, which is often anything but correct. An all too frequent scenario I encounter is sitting in the departure lounge, relaxing and looking out at an airplane-less gate, but the monitors declaring flight XX "boarding".