Vibration issue?

[ShadowReaper]

Hello i just bought the phone and i noticed the following when i tap the device even if the phone is off i have the feeling that there is a spring vibrating inside the device

Is this common for all devices or is there a problem with mine?

 

[seepage]

Look up haptic feedback.

Oops forget that. Just noticed it happens when it is off.
Sorry.

It sounds broken in that case.