This appears on a full white background or on anything with shades of green (dark grey scale or full red/blue are free of it).
I either noticed it after 50 hours (recently bought a LG 32GK850G) or it just appeared.
Then again this is a B-Grade and maybe that's why it was returned - it's on a central area of the screen.
Should I keep trying with online tools and poking the screen or is it just gone?
EDIT: Thinking about returning it if I can't fix it... I don't mind spending another 150£ for a new model, hoping I get it right.