Finally figured this out, I went to Substance Share and studied a similar wooden floor material (including bringing it into marmoset). I pulled up both their normal map and mine, mine looked much busier and more intense (especially the microdetail). I reworked my substance to match closer intensities to what they had and it's now lost the white lines. I think the general problem was too much information overlaying one enough in those areas (in this case the lines dividing the planks). This is how my normal looks now, much more dull and less contrast. Will slowly start bringing in details now and keep checking in Marmoset to make sure I'm not overlaying too much details in my normals.