Phantom Button Presses in Mazzer Espresso Grinder

I am embedding an arduino in my Mazzer Major espresso grinder to control the length of espresso bean grinding.

I have it all set up and working, but I'm getting phantom button presses. In 10 minutes of having it functioning, I had 2 phantom button presses.

Is there any way of adding hardware to the button circuit to filter out noise? I was thinking maybe a diode between ground and the resistor might help any noise coming from ground. That said, I'm not sure where the noise comes from, so I'm not sure what I can do to prevent it.

Does anyone have any tips?

Thanks!

How is the button wired? Does it have a pullup or pulldown resistor so that the input is not floating when the button is not pressed? If so, what is the value of the resistor?