Only an idiot doesn't test. The silkscreen is part of the Gerber file which includes all the PCB tracks. It is possible (although extremely unlikely) that a change has been made to a track or the wrong file is sent.
But it should not hold up anything, and it wont require CE testing.
The Gerber files are each for its own layer, so it's easy to see if no trace was changed in the copper layers of a new version of the board.
It probably is easy to see, but if you're about to produce half a million Raspberry Pi would you go ahead on the assumption that it "looks like nothing's changed", or would you build a few boards, test, then kick everything off?
Well, they said after the initial tests were passed, production of a new batch can start, and these will have the silk-screened logo. It makes no sense to test again.
A binary file compare and a signature (or more if needed) should be enough.
We are speculating here, and this makes no sense either. Actually I only hunt for any and all clues about the second production batch, as I'm sure mine is not from the first. I just want my Pi .