Yes, it happens. Especially if you have a domestic flight connecting to an international one and were going to upgrade using a SWU. Say ORD-SFO-NRT, and your SWU was not collected at ORD and you thought you were home free - WRONG!

They collect 500 milers (4 to be exact) from me every time. I choose not to debate it with United, because I still win out over the error. You can't be too greedy you know.

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When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.

- Leonardo da Vinci