Slight Rust Color in Leaves

Any reason for this?
almost has a copper look but not on the tips, only in the middle of the leaves, possibly some golden bud?

i hope to find out so..

imagine bud with golden hue.

sounds yum.

lol i think it could be mold or w.e not gold haha

Doubt its mold. Probably cal/mag issues. Do you use r/o water? Post some pics. That will help for sure