My fellow wildlife rehabber, Gudrun ("Goodie") has a squirrel that failed to grow. He seems in otherwise good health, but he's a midget. Goodie is keeping him and I thought you might like to see pictures of him. Here he is, eating an apple and posing with his Beanie Baby counterpart. His name is Parker and yes, he's an adult now.
P.S. I myself am not rehabbing this year, as I won't have time to raise anything before leaving for Greece.