Not gas / brake but brake / clutch once when transporting a model of car that usually was auto trans but this one was a manual. ( my auto / manual cars are different enough that this does not happen, )

I drive automatics with 2 feet as this gives much quicker transition and shother stopping distances, It also allows for "hovering" over the brake pedal when I see a potential "they are going to pull out" situation.

With a manual, the left foot only works the clutch unless driving the race car ( manual trans ) then left foot braking is sometime used to settle the car.

I bet the SUV driver was in an autotrans car and was driving with one foot.

While we are on the subject, when judging if another car is going to start moving and pull out, look at the wheel reletive to the fender. This gives a much earlier indication they are moving Vs looking at the body alone.