/vr/ - Retro Games

I recently upgraded to a consumer grade Trinitron Wega 27 inch, and playing my NES through AV out, I noticed something I've never seen before.
My video output flickers slightly.
It only happens for certain backgrounds, and I haven't noticed it on sprites.
In particular, certain background tiles in Brinstar in Metroid flicker very subtly, and it's driving me up a wall. Particularly, the tiles in pic related, the rightmost tiles right above the extra black space - those dithered tiles.
Does this happen on anyone else's NES? Mine is relatively unmodded, it just has a Blinking Light Win and the NES 10 chip is disabled.
Is this my PPU or the AV format itself?
http://retrogamesandhardware.com/nes-s-video-mod/
Will doing the mod above likely fix my issue? I'm opposed to replacing my PPU with anything stolen from arcade cabinets or anything like that.