Hi,
There doesn't seem to be a set pattern with senesence in GPO females. I've had some do exactly what yours is doing - turn grayish, and go downhill within a month or so, and I've had others lay their eggs and then go back to feeding almost nomrally and live on for another 6 months. I've had some lay their eggs all at once, and others just a few at a time. In my experience, the eggs last a LONG time, even though they aren't fertile. She may be eating or dislodging the older eggs. Yes - she is aerating or cleaning the eggs when she runs her arms over them.
We've decided to go with males only from now on - they live just a bit longer.
How long have you had yours, and about what size was it when you go it?
You may know the name Roland Anderson? He is THE captive GPO expert. Retired now from the Seattle aquarium, you can find a number of his articles in the public aquarium journal, Drum and Croaker. To locate them, go to this web site:
http://www.colszoo.org/internal/drumcroaker.htm
Then, click on "Content Pages" and search the resulting pdf file for the term "Octopus". I think he had a couple of major husbandry articles in that journal, but one is in the 1995 issue, right after one of mine(grin). Then, once you locate the articles you want, go back a page and click on "archived issues" and look them up.
Jay