Perhaps he just wanted to show off his new, shorter, streamlined haircut or maybe he simply forgot. Either way, it did not take long before the branded baseball cap was being pulled on.
Such a scenario could be construed as McLaren in a microcosm: strict, stuffy and uncomfortably corporate. Lewis Hamilton recently said his old team provided a "really controlled environment where you are restricted to do and say what you are told". He feels freer and more at ease at his new team, Mercedes-GP, he added.
Yet Jenson Button, who is entering his fourth season with McLaren and his 13th in Formula One, said it is a case of do not believe the gripe, while new teammate Perez added the public perception of the Woking-based marque is completely wrong.
"The freedom you have in this team is phenomenal. I was very surprised to hear that," Button said of his former teammate's negative comments.
"I've heard so many rumours and read so much about the way this team is and it is so far from the truth.
"Maybe people within the team are too afraid to say so, but it is really not like that. It's an open team, a friendly team and a team that will help you if you have any issues.
"When I came here, I thought it would be like people conceived it to be, but it is nothing like that. It is such a big family and they make sure you are comfortable, so that you are fully focused when it is time to go racing."
For Perez, it seems the cap fits.
The Mexican, who joined from Sauber in the off-season and is looking for his first win in F1 after three podiums with a middle-order marque, said the extra work that comes with McLaren is proof he is on his way to future success.
"People think here it is very strict and very cold, but it's not," the 23 year old said. "It's a great team, great family and I am very happy and lucky to be here, a part of McLaren.
"I am quite a bit more busy, but as well, the motivation changes.
"Once you know you can fight for wins and titles, the motivation is always there and as a driver you don't really care if you have to work more, because you have a team that is capable of winning, and that's worth it."
This weekend's Australian Grand Prix marks Perez's first competitive outing with McLaren and he is under pressure to perform for a team that has won 182 grands prix and eight constructors' titles.
He will not, however, resort to risky manoeuvres in his quest for a maiden race victory.
"The target is to win, always, and at McLaren you have that chance," he said. "I obviously have no wins in Formula One yet, so I want to win, but I am not going to drive desperately to get that win. What is most important is to score points race after race."
Following a disappointing pre-season where Perez and Button never once ran the same set-up, neither driver truly knows the pace of his car, and each is understandably refusing to predict performance – Perez said it would be "crazy" to forecast McLaren's place in the field.
Button, though, is confident the team's testing woes are behind them. McLaren proved sluggish in Spain compared to their rivals and Button admitted he could not have matched the top times posted.
However, having won at Albert Park three times in the past four years and with Australia's autumn temperatures notably higher than the cool climes of a European winter, Button believes a good weekend is possible.
Asked if he was frightened by rivals' pace in testing, Button replied: "If we were racing in Barcelona this weekend, yes we would be, but it's different here.
"It's hotter than the test, it's a very different type of asphalt and we know it's a very different circuit to Barcelona."
McLaren-Mercedes' sponsorship to end
McLaren-Mercedes have confirmed their seven-year relationship with title-sponsor Vodafone will end in December. The deal had been rumoured to be nearing its end for the past six months, but the British marque released a statement Thursday.
Martin Whitmarsh, the team principal, said the team was "immensely proud that, having been set a number of ambitious challenges by Vodafone back in 2007, together we’ve met or exceeded each and every one".
Jenson Button added: "It’s sad to see them go, but these things happen. They are putting their money and resources elsewhere; they are not just pulling out of McLaren, they are not going to be involved in Formula One."
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