Yes. Specifically for the 260 Rem round, Lapua brass is heavier and a little thicker than the Rem brass, which will decrease the internal case capacity, and raise your pressures. So, you have to reduce your load to accommodate this difference in case volume. Plus, the Lapua brass has thicker necks, and has more neck tension on the bullet. Both of these items will increase your pressure when shooting Lapua brass with the Remington brass load. It still may shoot fine, but it will increase your pressures, which will increase your speed. You have picked up probably 40-50 fps or more with the Lapua brass now, when running the Rem brass load. So, just watch for pressure signs, and back your load down if you need to.
Also, as you increase your pressures and speed, the POI usually goes up as you increase your load. So the POI shift up is normal.