64,000 Km check-up

I just had my 64,000 km check-up. They changed many things and parts but
they did not mention anything about replacing the brake pads. It all came to
$650 for this scheduled inspection.
They also had a diagnostic check and replaced the Oxygen sensor for another
$362. But now the CHECK light came back on and the rear brakes still make a
hooshing sound on slowing down.

Now, may I assume that the brake pads are fine enough for the next 10,000km
or so, and that another sensor might be gone bad?

cato