I'm thinking the same thing.Diesel oil turns black much more quickly than gasoline engine oil. That part is pretty normal, even after 50 hours.
However, the clean oil in the filter seems concerning, at least to me. If the oil was dirty out of the oil pan but perfectly clean in the filter it seems like maybe the oil is not circulating through the filter as it should.
As @Bee-Positive suggested, a conversation with your dealer might be a good next move.