This discussion may contain spoilers!
The scene where Clementine tries to give Sarah a tutorial in how to use a gun was awfully ominous, don't you think? Despite Clem instructing Sarah not to treat it as a toy, that's almost exactly what she ends up doing.
We can probably expect Sarah's irresponsible attitude concerning firearms to come into play in a later episode. This would be a nasty little surprise, as everyone's been expecting NICK to turn into the official "Ben" of season 2.
Maybe Sarah accidentally shoots someone dead. Carlos? Nick? Alvin? Luke? Kenny? Sarita? If Sarah were to kill Sarita, I doubt I'd be willing to get in Kenny's way if he wanted payback.