The Roosters prop gave Thurston a spray as he came off the field in the second half of the Tricolours' 26-16 win over the Broncos on Friday.
AAP understands Thurston, working for Channel Nine on the sideline, approached Leniu after full-time to clarify why the front-rower had a problem.
Thurston has told colleagues that Leniu then expressed his displeasure at comments the 2015 premiership winner had made in support of Ezra Mam in the wake of last year's racial slur of the Broncos' five-eighth in Las Vegas.
Leniu called Mam a "monkey" and was subsequently suspended for eight weeks by the NRL.
Thurston is a proud Indigenous role model and has stood up for those who have been racially vilified in the past.
He was scheduled to conduct post-match interviews in the Sydney Roosters sheds but his colleague Cameron Smith did so instead.
Roosters coach Trent Robinson spoke on the Leniu-Thurston incident after the match.
"It is just two passionate guys having a conversation about differences of opinion," he said.
"Someone speaking their opinion, I think, is good in this game."
When asked whether the Las Vegas incident was playing on Leniu's mind Robinson said: "Not that I know of.
"People are always going to have differences of opinion and you can voice that.
"It is okay to say 'I don't agree with you' both ends. No harm done … so long as people don't cross the line or say the wrong thing."
Robinson disputed that Leniu had crossed the line.
"From what I saw there was no crossing the line," he said.
"Spencer didn't approach anybody so I don't know why you are putting it on Spencer here. I think it is a discussion between two men. I don't think that is the end of the world."
17°C