does it look a bit like this? Difficult to see but sort of has patches. If so I think it is entirely normal - they scratch very easily and some "scratches" appear more as buffed patches
probably oil from your own hands. That or the fact that metals brushed metals don't reflect evenly because...well...they're brushed. You can get some metal cleaner (not polisher just cleaner) and give it a couple of swipes see if it evens out.
Thanks for all of the response. The watch is brand new so isn't scratched as yet but I am aware that the clasp is a "scratch magnet" !! I think it's just the grain of the steel and in certain lights looks dark in places. I'm not going to worry about it.
Ugh the dreaded desk diver marks. I barely breathed on my SMPO clasp and it got scratched. Now I'm over it, I'm just careful not to scratch the bracelet, case or sapphire.