I've had this a number of times.
Waaaaaaay back when, after 9/11, a TSA dude was reading my magazine as I was waiting to be gate-screened.

Another time, a pregnant Caucasian woman was interrogated, while her Middle Eastern husband (super nice guy) was standing there, holding their toddler, joking with me that it always happened to his wife.

So it is totally random.

(Last time I saw it was Amsterdam, not anywhere in the USA)