Chronic

It's most likely from temps. You're either getting a little chilly at night or getting a little heat stress while lights on. Normally you'll see purples push from cold temps but I've also seen red/pink push from heat in some strains. Yellowing can happen in both hot and cold conditions. If the yellowing originated more towards the bottom I'd suspect nutes more.

The red, and potentially purple, is either genetics, cold temperatures at night (68F and below), or both. Nothing to worry about as long as temperatures are not dropping below upper 60s at night. At some point it will hinder the chemistry of the plant if it gets too cold. If pushing hard with the light, it's possible the upper canopy is just paling a bit trying to keep up. More than one thing can cause chlorosis of new growth beyond that. Too much p or k is possible but i don'tthink that's the case here. Other coinciding symptoms are missing for that. Some trace elements might do this, but that'd be rare too -- ensure pH isn't wildly off and can confidently eliminate this possibility. hydro nutes and or soil of any worth would have plenty of trace elements. these things are measured in micromoles and the primary/secondar nutes are measured in millimoles. 10^-6 moles vs 10^-3 moles to put it in perspective. It doesn't take much to satisfy trace element needs.