Puggo - Jar Jar's Yoda said:

And doesn't C3PO say a very similar line in SW outside the cantina?

Yes he does. After a quick listen to the Spanish audio on the GOUT disc, Threepio's line "Oh dear what now? I don't like the look of this." seems to be present. Maybe someone who knows Spanish can confirm. The French and Spanish tracks also have Chewbacca's added vocalization in place when Boba Fett makes his entrance, in the scene where Lando betrays them.

Also, member Gregaton mentioned earlier this year: http://originaltrilogy.com/forum/topic.cfm/Hopefully-the-last-70mm-vs-35mm-ESB-audio-differences-thread/post/573758/#TopicPost573758 Yoda's "Ehhhh!" was there at some point before the SE. I have an old VHS tape with a recorded 1980 tv review of the movie, and a clip from that scene shown during the review features the "Ehhhh!"