Just need some help, week 1 into bloom.

Hey Guys/Gals

Just have a quick question. Im having some symptoms on some of my leaves which I cannot identify. Initially I thought it was wind burn due to the flow of air from my small fans but that would be on the outside of the leaves not inside.
Im running the Medi1 program in soil under 450w led if that helps.

Picture below.
 

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