5D mark II cheap plasticky creaking

My 5D mark II emits plasticky creaking sound all the time...

When I hold it normally in my hand the cheap plastic body at the edge of battery door is deflected and gives creaking sound like a split broken things.
In fact there's a split micro gap at the edge.

Could it be a refurbished unit. Since the plastic edge is in one panel containing the serial number that can be easily replaced with a new one.

Okay forget it, I'll go out a take photos anyway... but
Anyone have similar?