Fans were overjoyed to see the two, both 29, interacting over Twitter, writing things like, "Aww glad to see you and Kristin are still friends," "I'm so happy right now!" and "My babies!!!!"
Last October, ET chatted with Cavallari while she was promoting her Chinese Laundry Fall Fashion Campaign, and she opened up about how her relationship with Montag has changed since the popular reality dramas (and their famous feuds!) came to an end.
"I talk to Heidi all the time, yeah," she revealed. "It seems like she's doing really well and [she and husband Spencer Pratt] are really happy."