Does this pump also dispense marked fuels through the same hose?
In my province of residence gas stations near farming communities often sell “marked fuel” (fuel with an added red dye in it) that are taxed less, and which are intended for farming machinery, road work equipment, boats, and other non-highway use only. If you’re caught with red-dyed fuel being used for any other purpose you can be charged with an offence, and levied fines or other penalties.
If you dispense a small amount of regular gasoline after another purchaser had bought marked gasoline, the dye in the fuel remaining in the lines likely isn’t diluted enough to tell the difference — and you could (hypothetically) then be charged with possessing marked fuel without the proper paperwork.
(Anywhere I’ve ever seen marked fuels sold usually has a separate hose for the marked fuel to be dispensed from to prevent this from happening — but I don’t know your gas station or where you live, so maybe they rely on dilution rather than separation to differentiate?)