Jennifer Lopez and Ben Affleck Fans Spot Couple's Old Photo in Her Birthday Instagram Post

Jennifer Lopez celebrates 52nd birthday by kissing Ben Affleck on luxe yacht
Jennifer Lopez celebrates 52nd birthday by kissing Ben Affleck on luxe yacht
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@lacarba Ben Affleck and Jennifer Lopez

Eagle-eyed fans of Jennifer Lopez and Ben Affleck have noticed a very special item in the singer's recent social media post that marked the couple going Instagram official.

In the first of the photos Lopez shared Saturday in celebration of her 52nd birthday, the edge of a black-and-white snapshot featuring the "Cambia El Paso" singer and Affleck, 48, astride a motorcycle could be seen. The photo was taken in the early 2000s when they were first together.

Although Lopez's pal Leah Remini previously posted a photo of her and Affleck at her birthday party, Saturday marked the first time the lovebirds shared a glimpse at their relationship on their own social media accounts.

For more on Jennifer Lopez and Ben Affleck's trip in St. Tropez and other top stories, listen to our daily podcast PEOPLE Every Day.

"5 2 … what it do …💗," Lopez captioned the romantic images, which also included one of herself and Affleck sharing a kiss aboard a boat during their St. Tropez vacation.

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RELATED: Jennifer Lopez Is "Very Happy" with Ben Affleck as They Enjoy Her Birthday Weekend in St. Tropez

Various photos from the singer's French Riviera getaway with her boyfriend show the couple sharing smooches and taking in the sites of the coastal town.

One of the images showed Affleck with his arm around Lopez as they shared a walk together, and the pair leaning in close for another kiss.

In an additional snapshot, Lopez and Affleck were all smiles as they lived it up at the L'Opéra nightclub, where they celebrated with an intimate group of friends on Saturday. The two got cozy in a booth as they sang along to her 2002 single "Jenny from the Block," which featured the Oscar winner in the music video.

They didn't appear to shy away from showing PDA, either, as they were surrounded by friends and fans — some of whom posted videos from the festivities to Instagram.

RELATED VIDEO: Jennifer Lopez Says "Stuff" Started "Falling into Place" Once She Realized She Was "Good" on Her Own

A source told PEOPLE on Sunday that Lopez and Affleck were "having a beautiful trip," noting, "They celebrated Jen's birthday at a club last night."

"She looked gorgeous and very happy," the insider added.

A source recently told PEOPLE that the pair — who first connected romantically in the early 2000s and got engaged before their eventual split, but had seemingly rekindled their relationship as of late April — are "madly in love" and "the loves of each other's lives."

"Even though their split many years ago was devastating for Jennifer, she has never had a bad word to say about Ben," another insider added. "She believes that it just wasn't meant to be then and feels like they've been given a second chance."