The GH2 LCD shows a brighter image that it is actually being recorded at low f/.

I saw it referenced in the manual before I experienced the phenomenon, but I'm surprised to have not seen anyone else discussing it.

What's up with this? Is it only in certain modes this happens?

It is widely known issue. See my post at a thread above this.

Waldi, there are many threads, can you tell me which thread your post is located in?

which thread your post is located in?

You are already there.
http://www.dvinfo.net/forum/panasonic-lumix-gf-gh-series/491728-color-exposure-shift-gh2.html

It's true, this is a known issue. However, once you hit "RECORD", it *is* a wysiwyg display, it's only in standby mode that the brightness issue occurs.

Thanks, you're right I found it.