Oh its too bad they returned for such a short stay but they have done tons of educational work so if they must retire why not let them do it in California.
I walked and chatted with the keeper for a while that day - she said they are a male and female, 8 and 10 years old, no longer participating in any programs, and the female in particular is aging. She did look older to me, in her face, and with grey patches in her fur.
Also, they have been living in the Health Centre and the zoo has been moving animals out of there to make room for construction.