New Grower purpling or Def ?

[Mr Bloom]

Now its getting cold and im taking in air from outside I have noticed a strange colouration on some of the sweet leaves. Would you guys say this is just a change in colour or something more sinister ?

 

[Renaissance Redneck]

Looks like it's yellowing from tip out? Are the veins yellowing first, or can you tell?

Now its getting cold and im taking in air from outside I have noticed a strange colouration on some of the sweet leaves. Would you guys say this is just a change in colour or something more sinister ?