Chassis slightly bowed out over expansion port

Hi all,

I noticed the other day that this small strip of Aluminium over the rear rhs expansion port has bowed out slightly. It’s as if it is taken a knock on the corner and and had some plastic deformation from compression, but I’ve not dropped or dinged the laptop. I did some Kernel compilation and wondered if it was thermal expansion, as the laptop got warm, but not hot (about 50 Degrees) and it’s only thing I can think of. I have not moved the expansion card since i installed it, so I don’t think it’s that. The expansion card moves unimpeded in the slot.

It’s not a big deal (I don’t know how long it’s been like that) but I wondered if anyone else has observed this.