If you dilute a 10X buffer to 1X, the pH should move somewhat. One reason is that the change in ionic strength affects the practical pKa value. Dilution of an acidic buffer increases the pH; basic buffers should behave oppositely. Both Perrin and Boyd's book and Beynon and Easterby's book mention this effect. The change in pH upon dilution might be small enough not to worry about, but there is no harm in being aware of it.