On an east-west oriented runway the runway orientation will always be slightly different at each end due to the effects of convergence. Check out any example from the AIP, e.g. Heathrow 09L/27R:
09L: 089.67 Degrees True
27R: 269.71 Degrees True
Not a lot in I grant you but it'll always be the case - and more evident the longer the runway is.
NS