The 31-year-old DWTS pro -- who is paired up with Nick Lachey this season -- also shared that her son can already spot his mom on the dance floor.
"While we danced last week, my nanny actually said that [Shai] recognized me on TV," she recalled. "Last season -- when he was really young -- he didn't recognize me when I came into the trailer to see him, because I had so much makeup on and hair. He was like, 'Who are you?'"
Murgatroyd and Lachey performed the foxtrot on Dancing With the Stars, and while they did impress the judges, both admitted that there this is more work to be done on the 98 Degrees singer's form.
"It was tension in the shoulders. We have to work on getting down, so it's a lot of posture," Lachey, 43, explained. "Forty-three years of walking like a caveman, and now I'm expected to just ride it over night!"