When watching the new Blu-ray version of Star Wars: A New Hope I noticed C-3PO's half silver leg. I saw the original movie at the theater many times and do not recall seeing it before. Is this one of the alterations George Lucas made in converting the film to digital, or was his bottom right leg always silver?
The silver leg was definitely there in from the beginning :
On the Cover of The Story of Star Wars, a 1977 record album presenting an abridged version of the events depicted in the film Star Wars, you could clearly see C-3PO's half silver leg.
(To summarize my now-broken link: lots of people argued for hundreds of pages, and decided that the leg was ABSOLUTELY silver the whole time AND there was NO DOUBT it was gold originally, and everyone is really mad about it.)
Yes, in the original Star Wars: A New Hope the lower part of C-3PO's right leg was always silver.
I think the reason many who saw the first film don't remember the silver leg can be attributed to two things:
Much of the desert scenes where we see him involve brown and golden backgrounds that the leg, being reflective, would naturally pick up tones from.
Since all but that portion of him is golden, and we tend to visually track faces and torsos first, our memory and our initial attention was held by the golden color.