Interesting Matt, I take it you are referring to the base calibre Sellitas? There are three grades. I've personally had no problems with any SW movements over the last three years working on hundreds of them.
Considering Sellita supplied The Swatch Group with ETA branded movements once upon a time, its a no brainer than Sellita are just as good, if not better in some cases than ETA, Sellita even add an extra jewel in some of their movements, SW200, and SW220 (2836-2 type), so have 26J.
I had to get the correct tool.
Novodiac Spring Tool for ETA 28xx by Micky Aldridge, on Flickr
Novodiac Spring Tool for ETA 2801 by Micky Aldridge, on Flickr
Makes the job so easy.
I noticed that too when changing the crystal, tried cleaning them up with rodico, but appeared like some kind of mark caused by when the rep factory pressed the hands on.