I guess it depends on why you want to do it. Why do you want to?
The pH is never too high, usually the opposite, but for flavor you may want to add it if it needs it. I personally don't like much malic acid in my ciders, and sometimes prefer MLF'd ciders to get rid of excess malic acid so I don't see any reason to add more unless it's lacking some of the acidic "bite" of malic acid.