It is hard to say without seeing your exact issue, but I did notice a slight green cast with my 10ht. I have been able to fix this via the gain and bias by dropping the greens.
I have not done any formal studies but I have noticed that my gain and bias setting for hdtv and dvd don't always clean up the green cast out of native 480i stuff that has been upconverted to 1080i via my hd100 stb. For some reason some of this stuff still has a green cast to on the black areas. If I remember correctly I was able to correct it again by creating another set of gain and bias settings, but I did not keep those settings because I watch so little non HD or DVD material on the 10ht.