Andre-Pierre Gignac struck the game's only goal in the 77th minute at the Stade de la Mosson, capitalising on an error in the home defence to lift OM two points clear at the top of the table with three wins from three under new boss Baup.
But Baup, whose side also edged FC Sheriff Tiraspol 2-1 in the first leg of their Europa League play-off on Thursday, is remaining calm despite the promising start to the campaign.
"Nine points in three games - this is obviously a good thing," he said.
"[But] all this is temporary. You need a few more games than that. Let's see where we are after 10 games to assess our potential.
"It is especially important to take points to work on and improve."
He added on the club's official website: "The first period was complicated for both teams. There were many technical errors, players losing the ball. We had a better second period in terms of organisation and use of the ball."
Asked whether he planned to rotate his squad for Thursday's second leg against Sheriff at the Stade Velodrome, Baup replied: "We have not yet qualified. This is a team who are more complicated than they seem. We lead 2-1 but we must stay focused. The difficulty is to maintain our discipline, our game-plan. We must stay calm and keep our humility."
Defeat for Montpellier left them inside the relegation zone and still searching for their first win three matches into the defence of their title.
But coach Rene Girard will not be pressing the panic button just yet.
"There's no rush," he said. "Everyone should do a little more because we have to react.
"It is not that one thing does not work - just that we have made mistakes when we should not have.
"I cannot blame my players for not giving the maximum. At this moment it is not going in the right direction, but we will not give up and will keep working."
