+1 on totally fine and customary. There is no benefit in attempting to repair cuts in the tread. The rubber will get small cuts, but what's important to the strength and integrity of the tire is the cords beneath the rubber. If these are cut, the tire will start to bulge a little. A small cut through the cords of less than 2mm is usually inconsequential, but putting a boot behind it would be a good idea. If the cut is long enough, the tube will bulge out through the opening and pop. It's best to replace tires like this, though if it's borderline, you might consider booting it.