sa-update gives Can't locate LWP/UserAgent.pm in @INC ?

[Evan Platt]

Hello all...
Running SpamAssassin 3.1.3 on a OS/X box. Running sa-update gives 
"Can't locate LWP/UserAgent.pm in @INC". Can't recall if I've ever 
tried sa-update before.

Googling doesn't give much help, and a locate of UserAgent.pm finds 
nothing on my system.

Thanks.

Evan