Chancey and I came upon our friends Laura and Mokie on our walk this morning, so we inquired about the mystery kitty. Sad new and good news:
Sad news first: Laura couldn't keep her--apparently she and Mokie didn't get along as well after awhile.
Good news second: Laura found a home for her with a friend in Dallas.
So she's OK and taken care of, but I won't see her again.