DRV2604LEVM-CT: Button 3 responds

Hi,

I received a question from a customer about the evaluation board (DRV2604LEVM-CT), and I was wondering if you could support me.
The content is that even though customer didn't touch button 3, the ERM vibrates in response.

1. Is this the effect of static electricity?
2. Or is only button 3 sensitive? Is this an EVM characteristics?

3. Also, if there are any items to check with the customer, please let me know.

Best Regards,

Nishie