Ian Somerhalder and his ex-girlfriend and Lost costar Maggie Grace shared a love-filled reunion at PaleyFest Credit: Courtesy Maggie Grace

Making up for Lost time! Former Lost costars and real-life exes Maggie Grace and Ian Somerhalder looked closer than ever when they reunited on Sunday, March 16, at the show's 10th anniversary reunion panel at PaleyFest in L.A.

Seated side-by-side onstage, the two playfully teased each other as they reminisced with other cast members about their time on the show. An onlooker tells Us Weekly they had a "fun, flirty chemistry" -- at one point when Somerhalder referenced Grace, he leaned in and kissed the back of her neck.

The Vampire Diaries actor, 35, also shared a funny story about the Californication actress, 30 -- whom he dated in 2006 -- from their days playing step-siblings with sexual tension. In one scene from the first season, the costars were required to kiss. Prior to their last take, Grace stuffed her mouth full of garlic and took a few puffs on a cigar. "One of my proudest moments," she quipped of the prank.

Pictures of their happy reunion were posted to Grace's Instagram account over the weekend. One shot shows Somerhalder affectionately kissing the side of her head, while another shows her lounging on a couch with him and three other guys, including Lost's Sawyer, Josh Holloway.

"Losties reunion, pregamin it last night. @iansomerhalder @brynmooser #burky #joshholloway," she captioned the photo. "Love you guys so damn much."

Alongside another picture, this one of Grace wrapped in an embrace with Somerhalder and Holloway, 44, she wrote: "#PaleyFest? More like #LOVEfest! Such a great night, thank you to everyone who participated!"

Somerhalder was most recently in a relationship with his Vampire Diaries costar Nina Dobrev. Us Weekly revealed exclusively last May that they had broken up after more than three years together. Grace, meanwhile, has been linked in the past to TOMS shoes founder Blake Mycoskie.