After initially denying anything happened, Leah finally comes clean.
After the two appeared to be very flirty in the season premiere as they met up in NYC to film last season's reunion, fans who saw them post photos together on social media and Leah's own sister Victoria went into a frenzy -- asking if they had reunited.
Though they both denied it to Victoria initially, Messer copped to a New York hookup when asked about it by her friend Kylie via FaceTime.
"Jeremy actually showed up and we kinda hit it off at the reunion," confessed Leah. "I'm just left in my feelings a little bit, dammit!"
"Did you guys hook up?" asked Kylie. "No," Leah quickly responded. "Are you lying?" she pressed on. "Yeah," admitted Messer.
"We went out to the little pub across the street, had a few drinks and he's like, 'You're not going to your hotel tonight' and I'm like, 'Am I not going to my hotel room tonight?' And one thing led to another," she revealed. "We just had a good time and I was like dang it and now I'm leaving here wondering, is there more?"
Later in the episode, Leah opened up about her feelings for her ex -- with whom she shares daughter Addie -- while talking to her sister during a vacation in Costa Rica.
"Freaking me and Jeremy, I don't know what to say!" she exclaimed. "The weekend opened the door for possibilities. We had a great weekend. I think I talk to Jeremy every single day."
She went on to say that Addie was excited about the possibility of them getting back together, while Victoria added that Leah's other daughters seemed more than okay about it as well.
"All my kids want me to be with Jeremy, but I don't want to rush anything," she added. "Addie's six, she's not a baby and I don't want to confuse her. I don't want the fantasy of her wanting us back together to affect any of that. I want her to see us in a good place."
Looking ahead, Leah said her plan with Jeremy is to just "roll with it" and see what happens. Added costar Kailyn Lowry, who joined her on her Costa Rica trip: "I am supportive, you have my support!"
"Teen Mom 2" airs Tuesdays on MTV.