If you're growing in coco, I'd say it is fine, as the whole range between 5.5 and 6.5 is acceptable.
If you're growing in soil, the runoff is a bit too acid. In that case, aim for a feedingmix just below pH 7.0. This will probally raise your runoff pH a bit and the whole range (say 5.9 to 6.9) will than be fine for soil.
Good luck!