Curling leaf tips

My Penny is 28 days into veggie grow. She is very dark green and bushy. BUT, I noticed that some of the leaf tips are curling on the very tip. Plant is watered every 3 days and under 2 100w cfl and 4 tubes. Feed her once a week. Any ideas, I have seen curling but not just the tips like that.

yea that is a little odd ebcuase it is not the whole elaf just the tips. what ph is the soil?