It's been a little while but if that's true then it's a fairly recent change. The standard Airbus checklist had an after takeoff checklist for many years.
While the A320 has no "you're flying with the gear down, stupid" warning, there is a warning for excessive airspeed with the gear down. I believe it is triggered at 290 kts, so if that warning was never triggered, they never attempted to fly at such a speed, which is not a normal A320 profile.