"You've a good ear. I was doing some test runs out of country." And off planet. It wasn't a lie, not that he had any qualms about flexing the truth in order to protect identities, but he had to justify it somehow. It was what needed to be done.
This was one reason Oliver was one of Hal's best friends. The man had connections which, coupled with his charming personality, brought all sorts of interesting faces to even more interesting events. "I'm sure you'll have no trouble finding new friends with this group." He motioned back to one of the empty couches, "Want to grab a seat?"