No it's fine as long as it's a 9v pedal with center-neg, which it is. The power rating is the maximum power that the power supply or the port supports.
It will be fine, that just means you can't EXCEED 400ma. Your speed odometer may go to 140mph, but your car does just fine at 35mph
The pedal drains the power. It's not the power supply that "pushes" it. Problem is, when the pedals drain too much. Then the supply may overheat.