Where and when did this "makes me feel unsafe" thing start?

I went to a very liberal college (Brandeis) and law school (Yale) at the height of the original political correctness movement in the late 1980s. The PC crowd behaved badly in a variety of ways, but I don't recall that they ever tried to stifle discussion by claiming that hearing opinions that differed from their own made them "feel unsafe."

In fact, despite writing a book devoted largely to (primarily) left-wing assaults on freedom of speech, and sporadically blogging on related issues, I only started seeing references to students objecting to campus speakers, classroom comments, actions by student groups, and so on on "safety" grounds fairly recently.

But it's such a common complaint that one hears it from across the political spectrum these days, in a loud chorus of whining victimhood, from gay students who object to proponents of traditional marriage, and from Christian students who object to nondiscrimination rules meant to protect gays; from Muslim students objecting to pro-Israel speakers, and from Jewish students objecting to anti-Israel posters. Just today I learned (via Hans Bader) that Oberlin, supposedly one of the great liberal arts colleges in the world, has been in a tizzy because of a speech by the rather mainstream conservative feminist Christina Hoff Summers, which supposedly made students feel "unsafe" well in advance. And so on.

In no examples that I have seen has there been any actual threat or prospect of violence against the students complaining that they feel "unsafe."

This is a huge threat to the future of free speech nevertheless. Today's college students are going to be tomorrow's judges, and if they truly believe that "safety" means "never having to deal with opinions that disagree with one's cherished beliefs," then censorship has a good chance of gaining the upper hand over freedom of speech. After all, public safety can be a justification for suppressing speech, as with the "fighting words" doctrine.

Anyway, I've been wondering where and when this whole "makes me feel unsafe" thing started. Feel free to provide your theories in the comments, but I'm more interested in knowing your age, any other biographical information that you think is pertinent (e.g., "I went to the progressive Friends School in Pittsburgh"), and, to the best of your recollection, when and where you first heard someone say that someone else's non-threatening speech made them feel "unsafe."