SHe might *not* have been overlapping until that deviation from the line (especially if going for the bottle meant slowing down a tad). OUr guys always tell us "if you're the one behind, you're the one going to go down - so ride accordingly!"

I have brought the whole line down behind me, including pretty serious injuries (nothing requiring surgery, but people not back on their bikes for a month or two... some of them foregoing group rides/ pacelines for a *long* time). I *had* been happily cruising pretty much by myself, but then we regrouped.
LIttle bit after we started, somehow I was fourth in the group, and we weren't going very fast... and the light came off of the bike in front of me. It wasn't even actually near me... but objects in flight caused me to flick that brake with my left hand. Metal on metal, curses and scrapes, and about fifteen bikes all over the road. It looked like a battlefield scene from a movie... interestingly, not a single car went by, though some turned at the corner before us so they didn't have to.
This was about six years ago... I've had a couple of sort of close calls since (nudged wheels once, successfully dodged water bottle another time - yea, people drop 'em!) but mainly I consider pacelines an act of extreme intimacy (y'all have seen my drafting story, you know that's true :-)) and don't do it with strangers (well, unless the chemistry is *just* right!) Experience really does go a long way.
The *next* summer, when I was Saturday level 1 ride leader, two people told me on different occasions that they were getting back in to group riding but were nervous... that they'd been in a bad crash the summer before... my crash.