I found this word first in a Newsweek article about adjustments Silicon valley CEO's are ;having to make since the abrupt downturn in avaliability of venture capital: "The ones who took billion-dollar bites from the apple are suffering postlapsarian blues.
I searched for it, and found a couple quotes, e.g.:
How would you compare the rational ideal of the Houyhnhnms with the role of reason in Milton’s paradise? Are the Houyhnhnms Swift’s idea of what prelapsarian man might have become, the Yahoos his idea of what postlapsarian man has become? 203, 215

So it evidently refer's to the expulsion of Adam and Eve from Paradise, because Eve took a bite out of the apple.