Norris was exiting turn 10 at the Bahrain International Circuit as the marshal crossed the circuit under safety car conditions caused by the power unit fire suffered by Perez with just four laps remaining.
Whilst the footage of the marshal crossing the road raised eyebrows, the Briton insisted there was never any real danger with his speed diminished due to the double-yellow flags being waved.
"I panicked because it was the last thing I was expecting," said Norris.
"The guy didn't look left and right, both ways before he crossed the road. I mean it was a double yellow and I was going slow enough so there was no point in risking anything at all.
"He wasn't the most visible guy because, at that point, I am looking towards the sky, he is wearing pretty much black or dark blue and it wasn't that easy to see.
"All I saw was a bouncing fire extinguisher, a red extinguisher. It wasn't lucky but it was a bit of a crazy moment.
"The guy had some balls on him so fair play. I guess that was just one of the things that happened in quite an eventful race."
Norris came home fourth ahead of team-mate Carlos Sainz to promote McLaren back into third in the constructors' championship after Racing Point suffered a double DNF.
But Norris referred to the work put into getting the start procedure right ahead of the grand prix as the key factor in helping to build a strong race and ultimately, a key result in the championship run-in.
"A much better Sunday than what we were expecting," he conceded. "Not just myself but for us as a team.
"Between Carlos and myself, we gained a lot of positions off the line and we had very good starts and we put a lot of focus on that because it is a place you can easily gain two or three positions.
"We both did that. I was a bit lucky after the first start with the contact and avoiding almost being out of the race at turn two to P7 for the second start and again gaining positions.
"It was a good race, good strategy and good pace in the car made up for my mistake [in qualifying] and to end with a fourth and a fifth for us as a team is not what we were expecting so we can all be very happy."
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