The power jack is indeed angled on the Arduino Docks, although the pins are more or less straight; this is also the same case with the jack on the Servo Expansion. This seems to be part of the manufacturing process, but beyond that I can't say much (unfortunately I am not the hardware designer :()
The angle is given by the 2.5 degree dimension on page 5, area D6, but from the samples I see it can vary about a degree or so. I will revise the Arduino Dock drawing with clearer dimensions and notes on this when I release the Servo Expansion later this week. Thanks for pointing this out!
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