I figured that was canny misdirection on the part of the show. There have been several mentions now of Amma being in danger (the Chief says one of Adora's daughters in in danger and the other is danger...clearly Camille is the danger) or being worried over, so it seems like the time to imply that she'd be the killer's next target. Except, we know that the previous two girls are both tomboys who, in Amma's own words in the convenience store scene when Camille buys the sewing kit, not the cool or popular girls. It wouldn't be in character for Amma to be next. Also, the other murders were about a year apart, no? I do think we take away a lot of other interesting tidbits from that conversation with John though -- why is Amma hanging out with these uncool girls anyway? She clearly had some ulterior motive because this girl knows exactly how to manipulate people and enjoys it.
Right? Every episode has been getting shorter and shorter!