In Kim Stanley Robinson's Aurora:
During the return trip to Earth, (I assume) after the all the passengers are hibernated, the ship increases its spin gravity from 0.8g to 1.1g. Then after the ship blows up, the Humans theorize that it is to make the transition to Earth easier. But earlier the Iris colonists had absolutely no issues with the local stronger gravity. Did I miss the ship ever mentioning (or even implying) a real reason?
(book ending spoiler)