I too have a "vintage 3800" and just this week noticed the very same yellow pollution - gray predominates in the yellow nozzle check - so far, it will solve with a few cleaning cycles, but I am concerned about "end of life" issues too for this excellent printer.
Anyone else have this issue?
Yes. I'd already had an Epson tech in to replace printhead, capping station etc. 18 months later, the yellow nozzle check was coming out grey. I decided to bin the printer and buy a 3880.