[LyndsySimon]

Ditto. I had a late-2013 15” MBP that did it consistently, and it was worse when you touched the bottom of the chassis. My mid-2015 MBP did it slightly, and I’ve not detected it on my current-gen 13” MBP or any of my non-Apple hardware.

[Reason077]

It's noticeable on my 13" 2017 non-touchbar MacBook Pro, but only when you run your fingers along the part of the case above the keyboard.

It was much more noticeable on the MacBook Air, with pretty much the entire aluminium surface of the case having the issue.