on Saturday - which is run by Jenner communications - to share a compilation of sweet snaps from the "Kamp KoKo" trip including his daughter Dream, 4.
But one detail had fans thinking his sister had bounced back with her man.
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"Paradise with Dream #KampKoko," Rob captioned his slideshow, Dream on a boat in one.
His joining in is rare in itself since he skipped on sister Kourtney Kardashian's Portofino wedding.
But fans noticed something else; Khloe's ex Tristan, 31, appeared to like her brother's post.
He then un-liked it minutes later, but not soon enough.
'TRISTAN DROPPED A LIKE'
One riled-up Redditor noticed and wrote, "Tristan 'LIKED' Rob's post about Khloe's bday trip within the firs 5 mins he posted it....."
"...and now he's removed the like!!!!!!!!"
Another wrote, "Tristan liked."
A third claimed, "Tristan’s posted pics of him and Khloe with hookahs in their hands before."
That user seemed to think her ex was secretly on the trip - the gang flew out on another sister, Kylie Jenner's, private $72M jet - but other fans assured he's been spotted elsewhere.
Meanwhile, Khloe uploaded her own wave of photos Saturday which saw her swimming with her daughter True, 4, whom she shares with ex Tristan - and other cuties like Dream.
But the like-and-unlike spoke volumes since Tristan snubbed Khloe on her actual birthday - not posting any tributes.
Though that doesn't mean there isn't more evidence the pair are still in touch.
BOO-QUET OF FLOWERS
Last week, Khloe revealed she and her ex are on much better terms when she shared a photo of a huge bouquet of flowers he bought her.
The row of pink and red peonies - which she said are her favorite flowers - were placed in a long line down the center of her dining table.
Khloe shared them on her Instagram Stories, tagged Tristan and wrote, "Thank you."
The Good American founder seemed to quickly regret her decision, however, and deleted it.
She uploaded the same photo without tagging Tristan in it - all this before the tropical trip.
The move also didn't go unnoticed by fans on Reddit, where they speculated that it was the first of clearly many signs Khloe and Tristan are back on.
One wrote: "She does this every time. She ease's everyone into Trashcan with whatever gift her got her before she comes out publicly with him.
Just weeks earlier she met up with Tristan for an awkward reunion.
They shocked fans by going for a family lunch with their daughter True, four, in Calabasas and sharing a hug as they left.
Back in December, Tristan welcomed a son named Theo, now five months old, with Maralee Nichols, 31, back in December 2021.
TRISTAN SCANDAL
Tristan had an affair with Maralee when he was supposedly mutually exclusive with Khloe.
In January, he admitted in a lengthy Instagram post that he is indeed the father of Maralee's child.
After the NBA player revealed the paternity results, he also issued a public apology to Khloe.
"Khloe, you don't deserve this. You don't deserve the heartache and humiliation I have caused you," Tristan said.
"You don't deserve the way I have treated you over the years. My actions have certainly not lined up with the way I view you.
"I have the utmost respect and love for you, regardless of what you may think. Again I am so incredibly sorry."
Earlier this year, Khloe addressed the possibility of her getting back together with the Chicago Bulls player.
In an interview with ABC News, she said: "I still think he's a great guy and a great dad, he's just not the guy for me."
Asked what she's looking for in a partner, Khloe said: "I think at the end of the day, all of us aspire to have blissfulness, we want to be happy, and we want to feel safe.
"I did feel incredibly safe in the beginning, and I felt really good for a time," she said of her relationship with Tristan.
"I remember when he cheated on me right before I gave birth but I was still able to have him in the delivery room."