She watched the hesitation and the slight tightening of the muscles around his eyes.

A slight tightening of his eyes caught Rand's attention.

"There was a slight tightening in my quad," she said, "so I decided to hold off."

"Avrak," she said, and saw the slightest tightening of his mouth.

Then, with the slightest tightening of his lips, Spock adjusted the control back up.

Even a slight tightening of the lips can be a reliable sign that someone is angry.

There was a slight tightening in the back of her mind - and then a loosening.

Carridin showed no reaction beyond a slight tightening of his mouth at the name.

Only a slight tightening of the mouth betrayed the young man's feelings.

He thought he saw a slight tightening, but it could have been no more than a change in the light as she turned towards him.