appears in decent shape, i wouldnt worry unless it gets much worse.

the red stems: these occur all the time in reds/purples and is totally benign, caused by one of many causes. its a pretty standard occurance i think.

the leaves: like i said, they dont look too badly off, and can probably be fixed with minimal change to feedings. yellow is most likely caused by too little nitrogen in the diet, or possibly a slight pH issue.

solution: tell us the pH and nutrients, and consider upping the nitrogen concentrations very slightly to see what happens (wait for a second opinion tho)