An answer from Epson at last.
It's all a question of resetting the cartridge options and the procedure is here -http://kb.epson-europe.com/display/4/kb/article.aspx?aid=4010
It also affects the R2100 and R2400
It hadn't happened before and I wonder whether it's a driver issue, I have the latest version, which may be the problem. Oh well, all good at the moment.