Olympic medalist Michael Phelps might have another big thing on his mind besides swimming. Brittny Gastineau, the reality-turned-jewelry designer he has been seeing since around the beginning of November, is late according to a source.

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“She is heading back to LA now. She is so late and very worried. She has an appointment with the ob-gyn on Wednesday in Beverly Hills,” a source told RadarOnline.com exclusively.

Gastineau was spotted buying a pregnancy test in New York over the weekend. She was in town to celebrate the birthday of good friend and manager Darren Bettencourt and to promote her Tres Glam jewelry line.