A source tells ET that Nick was keeping very close to Andi at the Badgley Mischka show on Tuesday. "Nick appeared very desperate,” the source says, standing just a few feet from Andi while trying to get her attention.
But soon after, Andi couldn't take the undivided attention anymore, and she left the scene.
So far, neither party has tweeted about the run-in, but Nick did put up a cryptic tweet on Monday, writing, "I miss you so much it hurts sometimes."
Nick and Andi appeared to be on good terms through the finale in July 2014, before Andi, 28, made the classy move of sending Nick, 34, home before the final rose ceremony. That all changed when Nick put Andi on blast during the after-show in front of millions of viewers.
"Knowing how in love with you I was, if you weren't in love with me, I'm just not sure why you made love with me," said Nick.
Nick had a second run on the Bachelorette this past season, which again ended in his heartbreak when he proposed to Kaitlyn Bristowe. He opened up about the rejection to ET in July.
"I took a risk and I decided to trust the relationship and have confidence in it at the risk of getting my heart broken," he said of the ill-fated proposal. "I would rather be that person like I said than constantly questioning her and be a needy and insecure person."
Nick also seemed open to the possibility of trying his luck as the Bachelor.
"I would obviously feel really lucky and fortunate to be considered and asked. It's such a cool opportunity and it's very flattering, but at the same time, there are no guarantees to even find someone," he said. "I would seriously consider it, but I have to talk to my family and friends."