A mixture of cold temperatures and a new surface due to this being the inaugural race around the Las Vegas Street Circuit led to a race weekend in which many drivers complained of low grip levels.
Now, Stella has said that there are parts of the track that need to be 'fixed', including what he believes to be a slight bump right where Norris lost control.
“There’s a bump in that place,” Stella told media after the race.
“You can see all cars sparkle when they go through this bump. I think the combination of the bump and the cold tyres might have surprised him.
“I think that bump, if we carry on racing at nighttime, should be fixed, because the tyres will always be cold, low grip and it becomes a very tricky corner.
“Already during the weekend, we saw cases of oversteer in that place. So, independently of the timetable, we would strongly recommend that this bump is smoothened out.”