Okay, I *SERIOUSLY* doubt it, but is there any chance that she's following the oil life monitor on her car? Even with ideal highway miles I doubt most of them would get to almost 17k miles or more, but I just wanted to play devils advocate and raise the possibility. Similarly, maybe she's burning a quart of oil month and she actually checks and tops up her oil, so perhaps the oil is in better shape then we think (though even in the extreme unlikelihood of that happening, chances are the filter would be screaming for help at this point).
But her comment does show some insight into how she (and a lot of other people) think. Her comment seems to imply that she believes that since nothing noticeable has gone wrong with her car so far, that everything is fine. It doesn't appear that she's considered the fact that she could be damaging her car in such a way that it will cause problems in the future and reduce the overall life of the engine. And what is she expecting, that the car will give some signs that the oil isn't doing its job, at that point she'll take it in for an oil change and everything will be fine with no real damage done?
I wouldn't offer to change her oil regardless of how cute she is. Cause if she thinks everything is fine at over 16k miles on the oil, then she's going to think that YOU screwed it up when something goes wrong after the simple oil change