He hadn't expected the hug. Mike could never be confused for a guy that could see this coming because he was as far from being fluent in girlspeak or actions. Maybe he should have, but he didn't so it wasn't a surprise when he tensed up at the unexpected hug.
Just as he was about to return the hug awkwardly, she pulled away and left his arm hanging mid-move. Aborting the move with a cough, he smiled and shrugged. "Don't worry about it. I didn't mind."