I'm very weary of Libby..on the one hand i do think that she could well be a Hanso plant and that she has been from the time she was 'pretending' to be mentally ill..so as to keep an eye on Hurley and ensure that things went to plan [im thinking they all had agents or 'minders' keeping tabs on them..]..
On the other hand though its perfectly plausible that she is no more a mole than Jack is a diplomat
and is simply an innocent victim in all of this just like Hurley is. Perhaps she just didnt want Hurley to associate her with the stigma of being in a mental institute? Perhaps the thought of him knowing or recognising her would've brought on a set-back in her recovery?
I suppose it could go eitherway..but one things for sure..i'll be watching her closely these next few weeks!
there's just something about that woman!