Though she needed medical attention after partying at the Met gala last week, Rihanna was spotted partying late Saturday night at SoHo nightclub Greenhouse. The club featured a party by Get Right Records, and the label’s founder DJ Benzi spun during the evening with Silver Medallion, who is also signed to the label. While rapper Flo Rida arrived early and held court with friends, Rihanna arrived at 2 a.m. with security. Spies told us that the “We Found Love” singer “was dancing up a storm,” with her security detail and various managers from the club. Sources told us RiRi wanted to dance so long, the DJs kept the music going past the club’s usual 4 a.m. closing time. Rihanna last week attended the Costume Institute Gala at the Metropolitan Museum of Art, looking gorgeous in a slim-fitting crocodile Tom Ford dress. But the next day the singer posted a photo of herself on Twitter receiving an IV drip in her arm. Rihanna had explained on Twitter last weekend that she was battling an illness. By Thursday, the singer appeared healthy in Los Angeles, walking the red carpet with a smile at the “Battleship” premiere. Before partying at Greenhouse, behind-the-scenes photos of Rihanna from the set of her new video, “Where Have You Been” were posted on her Facebook wall.