Don't worry about it. Most probably a relative of one of the cockpit crew. And as others said, perfectly within the rules and deemed acceptable by the authorities.

Next time you're the only one in business ask the purser if you could join the crew in the cockpit for take off or landing (or better yet, the captain if he pops out during the flight). Crews are generally much more open to such request when coming from somebody in business class, and if accepted, I'm sure you'll enjoy the experience