Leaving out most of the specifics, there was a trap followed by a long fall, and a long fall would have killed the PC in question.
I allowed another character to make two saves in a row in order to pop off a levitation spell before the first one hit the ground, as an immediate action.
This is the PC's second character this campaign, the first died crawling through a fire in order to take an AoO so he could then attack someone the following round.
The players second character has been much more cautious.
I've killed one other PC as well. But it's also not the first time I've fudged the rules in the PC's favor to save them from being killed, and combined with this chapter of the AP generally being easier than the first chapter, I'm worried that the PC's will grow complacent.
Or worse; bored.
Part of the reason I allowed the save was because the dice HATED the PC all night.