Green cast in BW-printing on Epson 9900

[Arnebl]

A slight green cast has appeared in my black and white prints.
I a printing a large project with many images and from one day to the next a very slight green tint has started appearing in the images. It is probably so light that if I weren't to show them next to yesterdays prints nobody would notice, but I will, and it will show.
I print from grayscale files using the advanced B&W mode on an Epson Stylus Pro 9900. The paper is a simple Premium lustre photo paper 260.
But all settings shouldn't really be relevant as I haven't changed a thing and yesterday the prints were very pleasantly neutral and today they ar not.
Epson phone-support suggested a test of nozzles which turned up perfect (have kept them clean with regular cleaning) and weren't really of any more help.

Does anyone have any experience with this pheomenon?

[pspentax]

I always have the same inssue with the Lustre paper on a Epson 4800/9900 on B&W images, for color is a good choice.
I noted that if you see the image printed in daylight you don´t see the green cast but in some home lights you will see it. I think this is the cause for you have started seeing the green cast.
In ABW for B&W images on other papers like the Epson Velvet, Epson UltraSmooth and the Breathing color Vibrance rag it´s fantastic.