Thrips, spider mites, and slugs do most of the damage to my daylily leaves. Trips and spider mites turn foliage kind of pale silvery or yellowish and you get spots of yellow from where they suck the juice from leaves. Hate thrips the most they damage the flower scape's as well. The leaves with the brown on them looks like slug damage.

Looks very good to me, nice and green. You can pull or cut those couple brown bottom leaves. I moved my Lime Frost this spring and I wish mine looked the same :) Guess it didn't like being disturbed.
Pretty bed, btw!