According to Lowry, they weren't recomped:

Whenever anyone lit up a lightsaber, it was done with an optical effect, and all of the opticals at the time were done on film--there were no digital effects. So every time you go to a lightsaber scene, bang, you drop two generations of film. It gets grainier and, as it's going through an optical printer, you have different characteristics in terms of contrast. And those are things we have to match up with the scenes immediately before and after. It took a lot of effort to match precisely the granularity, the contrast, and the sharpness. They flow very nicely now and, frankly, in the original movies, there was a distinct change. We were able to eliminate that change, and to me that's a very strong contribution to the storytelling process--removing something that prevents an audience from being drawn in.

However, Zombie reckons they were re-rotoscoped (here).