But more recently, the 2008 world champion said on Twitter that he and Rosberg are "cool, still friends, no problem".
Not everyone is convinced all is well.
Speed Week correspondent Mathias Brunner said Hamilton's social media posting "seems like a bandaid for a blister -- it helps but pretty soon it falls off".
And the Daily Mail's Jonathan McEvoy doubts Hamilton even penned the 'tweet' or picked out the old photo of the then teenaged teammates riding on unicycles.
"The timing was mysterious," he wrote, "as only a few hours earlier a Mercedes spokesman said he thought Hamilton was in the air, travelling to North America" for the Canadian grand prix.
The same team spokesman insisted that Hamilton "tweeted independently of them", McEvoy added.
Whatever the truth, Mercedes team chairman Niki Lauda claims the worst of the saga is now over.
Asked about Hamilton and Rosberg's supposed reconciliation, he told Osterreich newspaper: "Lewis has now accepted that Nico won in Monaco and he (Hamilton) was second.
"There is no shame in that," said Lauda. "In Montreal we will get together again and discuss everything calmly, and afterwards the fight for the world championship goes on with both of them in equal cars."
The triple world champion, however, acknowledged that more conflict is likely.
"Having two alphas sitting in the best car is of course tricky," said Lauda. "But at least it makes the races interesting given the superiority of our team."
Lauda said he is well qualified to help keep the situation under control.
"I know a situation like this very well thanks to Mr Prost," he said.
"We let our drivers race against each other without restrictions, because while tension is quite normal, it can also escalate. Then I can get involved as a mentor."
Lauda tipped the Hamilton versus Rosberg battle to be fascinating this weekend in Montreal.
"Nico was clearly faster over the Monte Carlo weekend," he said, "but now Lewis will be doing everything to fight back, which of course is stressful for us.
"But for the fans and the sport there can be nothing better."