Sam Altman appeared to troll Elon Musk by dredging up a years-old Twitter post

• Elon Musk filed a lawsuit against Sam Altman and OpenAI last week.
• Following the news, Altman resurfaced an old exchange with Musk by replying to the Twitter thread. 
• Altman was seemingly being sarcastic by writing "anytime" after Musk thanked him in 2019. 

Sam Altman seemed keen to attract Elon Musk's attention by resurfacing an old conversation with the owner of X.

Back when the platform was known as Twitter, the OpenAI chief replied to a 2019 exchange he had with the billionaire after Musk filed a lawsuit against him and OpenAI.

Altman wrote "anytime" next to a salute emoji in the conversation thread, in which he had previously praised Musk and Tesla.

"It's gross seeing so many root against Tesla. Be the person on the side of the climate and innovation, not the person hoping to make money on puts," Altman wrote in 2019. "Also, betting against Elon is historically a mistake...and the best product usually wins."

Musk wrote back at the time, "Thanks Sam."

Musk sued Altman and OpenAI last week, accusing the company of jeopardizing its mission to benefit humanity by partnering with Microsoft.

OpenAI was founded by Altman, Musk, CTO Greg Brockman, and several other engineers and scientists as a nonprofit, its website said. The pair have had a complicated relationship and have exchanged jabs over the years.

OpenAI seemed to dismiss Musk's claims in the lawsuit in a memo sent by one of its executives, Jason Kwon, which Axios and Bloomberg obtained.

Kwon suggested that the lawsuit "may stem from Elon's regrets about not being involved with the company today", the Bloomberg report said, citing the memo.

OpenAI's chief strategy officer appeared to rebut Musk's lawyers' argument that OpenAI has become a subsidiary of Microsoft.

Kwon said, "We decide what to research and build, how to run the company, who our products serve and how to live out our mission."

He added, "We also directly compete with Microsoft to deliver the best value and products to businesses, developers and everyday people. As we know, OpenAI is the creator of ChatGPT and ChatGPT for Enterprise, while Microsoft offers Copilot and Copilot for Microsoft 365."

In a separate memo Altman sent to OpenAI employees, obtained by Bloomberg, he dubbed Musk a hero. Altman said that he missed the billionaire, who he says used to compete by building better tech, the report said, citing the memo.

OpenAI didn't immediately respond to Business Insider's request for comment made outside normal working hours.