After launching their Elizabeth and James line in London Tuesday night, Mary-Kate and Ashley Olsen were already on their way out of Heathrow yesterday when they had a celebrity sighting — Gwyneth Paltrow. The three blondes and their respective entourages joined forces for a bit as they made their way through the airport. With recent Fashion Week trips in common, the three fashionistas had a lot to chat about as they waited for their flights.