Experienced paddock dwellers are contemplating the notion that Sebastian Vettel might soon call time on his F1 career.
The German won four titles for Red Bull before switching to Ferrari last year, but those who have worked closest with Vettel, who is now 29, sense a change.
"Some things we have seen before with him, but it has been a bit more uncharacteristic than in previous years," said Vettel’s 2014 teammate, Daniel Ricciardo.
The Australian is referring not only to Vettel’s moving under braking that cost him the podium in Mexico, but his foul-mouthed antics over the radio which earned him an investigation and near-penalty by the governing FIA.
Vettel’s former boss Christian Horner has also sensed Vettel’s change.
"It is not an attribute he had when he drove for us," he said. "Obviously his frustration he is vocalising, and everybody can hear that."
Curiously, both Vettel and Ferrari are not willing to discuss the terms of a new contract for the German beyond 2017, during a season in which teammate Kimi Raikkonen has regularly looked the better Ferrari driver.
Former F1 driver and now veteran commentator Martin Brundle said: "I’m beginning to think Sebastian Vettel won’t be in formula one for the long haul.
"He came so young, he broke so many records. I just watch him at work and he’s lost his mojo."
And an unnamed figure told the Times newspaper this week: "Seb could just walk away.
"He has won four titles and he has nothing to prove. He is a private man with a family. He doesn’t crave the spotlight and he may think he has had enough.
"It would be a shame, but he could do it."