No, it's in the actual books -- I think it first cropped up in Cerulean Sins, when Anita was having a heart-to-heart with JC and/or Asher about her definition of sex = intercourse, while theirs is a little bit more liberal (because they're gay French and therefore made of sex?) and what they're comfortable with doing isn't the same as what she's comfortable with doing, blah, blah, bitchcakes.

It may have been briefly in Narcissus, but I'm blotting that out of my memory.

I know it made a brief comeback in ID, much to my disappointment.

I probably wouldn't be so irksome about it if she hadn't labelled it as "American" vs "European" sex, because of the generalisation of it all. Sex is subjective, I wouldn't have minded if she'd written Anita saying "this is my definition of sex,"