The meeting raised eyebrows to some degree given the public fallout between the pair towards the end of last season.
Brown wrote a letter to FIA President Mohammed Ben Sulayem accusing teams who breach the budget cap – as Red Bull was found guilty of last year – of “cheating”, a remark that hugely displeased Horner.
The friction between the pair has now seemingly eased as Red Bull moves towards using its own PUs from 2026 when new regulations come into force.
Asked about the meeting with Brown, Horner initially joked: “I thought he was coming for lunch!”
Speaking in Bahrain ahead of this weekend's grand prix, he then added: “It's obvious that as a power unit manufacturer for 2026, it's inevitable that discussions are going to be held regarding potential powertrain supply.
“It's only natural we would speak with potential customers.”
Yet Stella remarked: “We have a solid partnership with HPP.
“At the same time, obviously looking far forward, you want to understand what's available, so I think that's natural.
“It shouldn't be too much of a surprise”.