If you're wondering why Peta and Sharna are so close, it's because they've know each other for a long time. As Sharna explained to us, "I've known [Peta] since I was, oh, 20, living in London and competing, when we were both competing on the same circuit together." Not only that but the pair "danced on Burn the Floor together for a long time. About six years, actually."
It's always nice to see the pros hanging out together outside of the show. Happy b-day, Sharna!