I’ll wait for the bluray release to be sure about that :
http://i.stack.imgur.com/lJE7Q.png
But if you’re positive about it, ok I believe you. That’s weird in fact, in term of continuity, making a character being changed off screen. So that way 2 different action figures can be sold ?
I’m 100% positive. I thought I saw it the first time but wasn’t quite sure, but on subsequent viewings (I’ve seen it 4 times now) I saw that it definately was fixed back to gold by the end of the film. And I’m pretty sure I’ve seen someone else mention it on here too. Threepio also makes mention to BB-8 (I think) about getting his proper arm re-installed while he still has the red one at one point.