http://classic.7sage.com/lsat_explanations/lsat-57-section-3-question-11/

This is a challenging question - largely because it hinges on 1 word - permanent.

It's a weaken question, but the word permanent is crucial to it.

If I didn't see that word, I dunno what would happen...

I feel like this may be a pattern for challenging LR - where it comes down to a subtle distinction based on one word....

Any thoughts on how to be vigilant about it?

Perhaps... if you're having trouble with a question, double check for hinge words?