It is possible he would have managed to exit without being noticed, if there were more other people around to distract Yelena from catching the sound of the door and the hint of movement out of the corner of her eye.

Nope is also very much her thought, when she turns to follow him, quickly but not at any unusual level of rush. There's less anger then would have been present in her voice if they had actually spoken the last time he saw her, but she does still sound far from pleased.

"What are you doing here?"