I have this happen too to a bunch of stuff using the tint effect and even stuff that has no webGL effects at all, but only when a webGL effect is being used on something. Ashley said it's a webGL problem my computer is causing but I don't know if that's the case because it happened for my friend too and he has a totally different computer set up so I find it hard to believe all of us have the exact same problem happening with totally different computers.
The way I get it to stop is I go to my HUD layout and show all the layers which have a bunch of stuff on them all and then it usually fixes itself when I scroll the screen.