Kate Middleton resurfaced on social media with her first post since undergoing successful abdominal surgery in January, but some critics are convinced that the new photo isn’t real, RadarOnline.com has learned. The snap, reportedly taken by Prince William, 41, and shared in honor of Mothering Sunday in the United Kingdom, showed the Princess of Wales, 42, seated alongside her children Prince George, 10, Princess Charlotte, 8, and Prince Louis, 5. “Thank you for your kind wishes and continued support over the last two months. Wishing everyone a Happy Mother’s Day. C,” Middleton wrote in the cap…