Stu is very down to Earth, so it's not that exceptional to see him give masterclasses to small groups. He's been to my former music school in west London several times, given masterclasses and then stopped to speak to us afterwards, and he's been at the London Bass Guitar Show in the past (at the Hartke stand when I met him), relaxedly chatting to punters like me. (He even said he remembered me from one of his masterclasses at the school.)
If you keep track of him, you'll probably be able to see him in person again