Formula 1 could introduce a rule clarification after Sebastian Vettel started Sunday's Chinese Grand Prix out of position.

Officials "noted" but did not penalise the Ferrari driver for being left of his painted grid 'box' in Shanghai.

"I didn't want to be on the line on the wet track, and there is nothing in the regulations about not doing that," Vettel said afterwards.

The incident went unpunished, but former F1 driver and Shanghai steward Mika Salo confirmed to Turun Sanomat newspaper that the officials looked closely at what happened.

The Finn said that what was discovered is that the rules are not clear about being strictly within the lines, because some grids like Monaco are complex and curved.

"When such an anomaly exists, we decided to let Vettel go in this case," said Salo.

"It could have been a warning, but it's better to have a more specific rule for these cases."

Another incident that went unpunished but not unnoticed on Sunday was the clash between Sergio Perez and Lance Stroll.

"If someone had been penalised, it would have been Stroll," said Salo.

"In the previous corner he left room, but then in the next he turned in when Perez was already next to him."

Still, no penalty was applied, in accordance with a new philosophy in F1 about letting the drivers get on with racing whenever possible, even if they touch.

"I have always believed this is the right approach," Salo said. "The penalties had become too much.

"Really, the penalties should only be for things like overtaking under yellow flags or when behind the safety car, or when there is a gross violation of the rules."

The championship continues this weekend with the Bahrain Grand Prix.