Late last year I was selected for an SSSS inspection (Secondary Security Screening Selection) when flying from Orlando to London.
This only involved a brief chat with a TSA man, and a good look in my carry on baggage.
I found out afterwards that this was due to me purchasing a one way ticket from the USA, a few hours before the flight was due to depart.
It probably didn't help matters that I have lots of passport stamps from an African country which is on the American "watch list"