Well, my username says it all... :)
I think one of my does that I aquired is stunted. Reason being, she doesn't grow, lol. I gat her from a trade with a dear friend, with her in milk dam. I got her at two months and she is exactly the same way. Even weirder, she has been nursing ever since she was born! She is five months old now and is the size of a 2 month old.