@Bas: Was a different detector then the LHC,..
They did the experiment 5 times, same results,.. I heard it was about a 7 meter difference over a 170 km track (dont have the exact figures, heard it on the news).
Anyway, all that changes in Einstein's theory, is the constant of c.
So now it's not 299,792,458 m/s but 300,000,00 m/s (based on my own experiments).
I always found that first number rather silly. If something is so absolute, why cant it be a nice round number,..?