Big Bang problem, need help.

This is my Big Bang. It is 5 weeks into flower and started showing some rust looking spots on the leaves closest to the top of the buds. Attatched is a pic. I am thinking that i may have some trace nutrient problems here.
It is in Roots organic soil and i am using Gardening Magic nutes.
I noticed this the last few days and flushed the plant yesterday and it looks slightly worse today. Any input would be appreciated.

Thanks in advance.