What is this?

Outdoor. Acapulco Gold Gem by Canuk Seeds. Week 5 into Veg.

Dark blue/purple color on new leaves (only on one branch, there's another set of new leaf on other branch with normal color) Noticed this morning and probably wasn't there yesterday. It seems chalky/matte. It's still there after a mild water shower. I carefully tried scraping some, it's doesn't seem external but rather leaves themselves are of that color. Anybody know what's going on?

Apologies for the low res picture. Have shitty camera on my phone.