Rudd doubts that. You don't just walk up before the race and dump something in your fuel, then stand back to see what happens. I believe a lot of planning had to go into it. Currently, each car goes through inspection before qualifying and before each race. But those inspections basically check only height, weight, aerodynamic contour, etc.
Teams fill their fuel cans with gas from a supply provided at each track.
Such was the case in the recent incidents. If somebody's up to something, whispers start to spread. The last thing I want to do is get beat by somebody who's not legal. I resent the heck of of it, and so does every other driver who's playing fair. I hope they get 'em all.