Outside of Kaley Cuoco’s immediate family, David Oyelowo may have been the first person to know the actress was pregnant.

While attending Club SI in Las Vegas for the F1 race on Friday, Oyelowo, 47,

spoke exclusively with PEOPLE about his upcoming film with Cuoco, Role Play, which is set to be released on Prime in January.

According to the actor, when the duo filmed the movie, Cuoco, 37, hadn’t told anyone she was expecting, but the signs were there.

“We were doing this scene in a hotel, a disused hotel, which you could tell had been disused because of how badly it smelled. For anyone who’s been around someone who’s pregnant, their sense of smell goes through the roof,” Oyelowo explained. “She was just nauseous with the smell of this hallway. So every time we would do a scene, and we would call cut, she would say, ‘Can you smell that? Is that bad?’ ”

Oyelowo then noted that The Big Bang Theory alum would actually spray perfume on her hand to smell that instead, and though he initially thought Cuoco’s actions were “weird,” he then wondered if there was something going on.

“It got so weird that she had to eventually tell me that she was pregnant, and then I had to keep this secret,” he said. “So that’s something that probably shouldn’t have happened but did, and was very funny.”

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Cuoco and fiancé Tom Pelphrey welcomed daughter Matilda earlier this year on March 30.

The couple announced their firstborn’s birth on April 1, calling her the “new light of our lives” alongside a set of family photos shared on Instagram at the time.

Remembering the moment when Cuoco told him that she was expecting Matilda, Oyelowo said he was filled with emotion.

“She told me this, and I started crying, and it was completely inappropriate given the scene,” he said. “It was meant to be a scene in which I definitely wasn’t supposed to be crying.”

“She’s a great human being,” Oyelowo added of Cuoco.

Oyelowo also detailed his first experience meeting Cuoco, telling PEOPLE, “She presented me with 20 questions that I had to give the answers to so that we knew each other instantaneously, and we had to ask each other these questions.”

“But that’s just her. She is a human walking, living, breathing icebreaker. Everywhere she goes, it’s sort of like all reservations get broken down by her,” Oyelowo added. “She’s just a joyful spirit.”