In the early stage of flowering it will be ok , when the buds will be packed it will be a bit too much of humidity so a bud rot / mold can occure.
For now keep it like that , after week 5 of flo for the photoperiodic it will start to be an issue and after week 6 it could be harmfull
I agree with @spinnnn. You need to get the humidity lower as the buds pack on weight and girth. Even with a oscillating fan Leaving it high towards the middle and end just increases the chances of the buds getting mold/rot.
64% is not of any concern, given that you have a well-fanned grow space.
If you do not have a fan circulating the grow space, you need to either lower the RH% or install a fan.
Good looking grow :)