The couple kicked back at the Delano Hotel, where Jay-Z was working with Bing to launch the DECODED search experience, an Internet scavenger hunt based on his new book. And though it was Beyoncé making headlines, she left the spotlight all to her husband.
As the rapper gave interviews, Beyoncé slipped away into a poolside bungalow, where she ordered snapper, salad and sparkling water from the hotel's Blue Door Fish.
"She was wearing a skintight dress that left nothing to the imagination," an onlooker tells PEOPLE. "There were no remote physical signs that she was pregnant."
It wasn't until later that she emerged, smiling, to hear Jay-Z give a speech.
"She almost went unnoticed. She really made it a point not to be in the spotlight, that it was his night," says the onlooker. "At one point, she actually introduced herself to a Jay-Z fan, who was shocked that she was standing there."
Later in the evening, the couple retreated to a bungalow together. "They were adorable," says the onlooker. "She was sitting on his leg and they were watching TV. They were lovey-dovey."
On Thursday's Ellen DeGeneres Show, Beyoncé's mother, Tina Knowles, denied that her daughter is expecting – yet.