Some diesels at light load burn some oil. some do, some don't. And a qt in 25-30hr is not that bad at all. Just consider it in the cost of running.
Can also try running it hard for a day, maybe it has been babied and rings could use a bit more seating. But usually once they get some hours on them, rings are either seated or not. Cheap enough to try.
But if nothing changes, don't let it bother your enjoyment.