I always tense up when I walk through a security gate. Not the ones at the airport: I assume that I'm going to set those off, the ones at the library. Even if I'm not carrying any library (or Blockbuster) material. I just tense up. And of course, yesterday I set the alarm off. Not because I was trying to leave with unchecked items (although I have been known to do that), but because I was leaving work with a public library book. The PL never desensitizes anything, since there aren't any security gates at my branch, even though there are downtown.
And, to add injury to insult, our gates don't just make noise, they lock a swinging turnstile. So, instead of swinging out of the way, it hit me. At "waist" height.
I wonder if I can claim workers' compensation.