I've never seen anything quite like that.

One time we were all set to push back when the captain made an announcement that the fuelers had loaded on too much fuel for our (short) flight and that we'd be delayed for a half-hour. His answer to the obvious question (Why does it take so long to offload some fuel?) was that they have lots of big trucks with big pumps to load aircraft, but only a small truck with a much slower pump to unload them.