I've heard/read a few theories that this Yoda was designed to go with the RAH figures and that is why he isn't in the deformed style like the others. Something along the lines of it was too difficult to do a true RAH figure for someone as small as Yoda, so they made up this vinyl Yoda to take the place.
Based on the sizes listed for the figure, the theory works for me. Scale-wise, he is too tall to fit with the other Vinyl figures, but he seems to be a pretty good scale match to the RAH Jedi Luke, so maybe ther is something to that rumor/theory...