I was 'spotted' a couple years ago, and the TSO even followed me into the restroom and continued interrogating me while I was in the stall taking care of business.

I don't know why it never occurred to me before this thread, but: obviously they aren't just focused on reading your micro-expressions, because unless there is an elaborate set of mirrors and hidden cameras I don't know about, there was no way the TSO had visibility of my 'micro-expressions' while I was in the toilet stall being interrogated.