They certainly look like machine marks to me, but I'm no expert. That's easy to explain: As Neill Gorton from MFX himself has told us, they were given one specific hero prop to work from, and they've made every possible effort to ACCURATELY reproduce that prop in every detail, EVEN DOWN TO THE FINISH OF THE MACHINED ALUMINUM PIECES (i.e. how shiny or dull they are.) On the prop they were given to work from, the emitter head had a slightly duller finish than the other machined aluminum pieces, and they have attempted to reproduce that look as exactly as possible.
Myself, there's part of me that would have preferred it if the prop looked exactly like the 2 prototypes they made at some point in '08...
...with their highly polished aluminum components. But the rational side of my brain tells me that those prototypes were idealized in that regard, and that the final prop replica we've received is that much more accurate to the filming prop because they've made every effort to accurately reproduce the finish of those aluminum components. :cool
Also, keep in mind that for film and TV, a chrome-like, highly polished appearance is generally NOT desirable on a prop. It makes it much harder to film, because the glare of the lights off of chrome-like bits makes it utter chaos to film them, and then there's the reflections. In a really good closeup, you'd see the cameraman reflected in the prop! So, a duller finish is actually preferable for filming purposes. That's why on
Star Trek: The Next Generation and its various spin-offs, the communicator badge props were NOT chrome-like, nickel-plated metal or vac-metalized plastic like the authorized replicas sold in stores. The REAL props were actually resin painted with metallic paints. On camera, they look like metal, but the level of shine is controlled so that they didn't get all that glare, or the reflections where you would have seen the filming crew on set.

*sigh* So, what does this mean, exactly? Does every single one have this apparently faulty LED that could go bad at any time? Are we ALL going to have to send our Sonics back for repairs? What about those of us whose Sonics were sent out in the second batch that shipped on or after October 12th, the ones that were supposed to have been corrected before shipping? Are ours going to be fine, or did we still end up with a product that could stop working at any given moment?!? :confusedAgain, my opinion is that it looks like it's been worked with tools TO ME. But as I said before, I'm no expert.